Action not permitted
Modal body text goes here.
Modal Title
Modal Body
PYSEC-2026-2151
Vulnerability from pysec - Published: 2026-02-21 06:17 - Updated: 2026-07-13 05:48
VLAI
Details
Flask is a web server gateway interface (WSGI) web application framework. In versions 3.1.2 and below, when the session object is accessed, Flask should set the Vary: Cookie header., resulting in a Use of Cache Containing Sensitive Information vulnerability. The logic instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked. The severity and risk depend on the application being hosted behind a caching proxy that doesn't ignore responses with cookies, not setting a Cache-Control header to mark pages as private or non-cacheable, and accessing the session in a way that only touches keys without reading values or mutating the session. The issue has been fixed in version 3.1.3.
Severity
4.3 (Medium)
Impacted products
| Name | purl | flask | pkg:pypi/flask |
|---|
Aliases
{
"affected": [
{
"ecosystem_specific": {},
"package": {
"ecosystem": "PyPI",
"name": "flask",
"purl": "pkg:pypi/flask"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.1.3"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.1",
"0.10",
"0.10.1",
"0.11",
"0.11.1",
"0.12",
"0.12.1",
"0.12.2",
"0.12.3",
"0.12.4",
"0.12.5",
"0.2",
"0.3",
"0.3.1",
"0.4",
"0.5",
"0.5.1",
"0.5.2",
"0.6",
"0.6.1",
"0.7",
"0.7.1",
"0.7.2",
"0.8",
"0.8.1",
"0.9",
"1.0",
"1.0.1",
"1.0.2",
"1.0.3",
"1.0.4",
"1.1.0",
"1.1.1",
"1.1.2",
"1.1.3",
"1.1.4",
"2.0.0",
"2.0.0rc1",
"2.0.0rc2",
"2.0.1",
"2.0.2",
"2.0.3",
"2.1.0",
"2.1.1",
"2.1.2",
"2.1.3",
"2.2.0",
"2.2.1",
"2.2.2",
"2.2.3",
"2.2.4",
"2.2.5",
"2.3.0",
"2.3.1",
"2.3.2",
"2.3.3",
"3.0.0",
"3.0.1",
"3.0.2",
"3.0.3",
"3.1.0",
"3.1.1",
"3.1.2"
]
}
],
"aliases": [
"CVE-2026-27205",
"GHSA-68rp-wp8r-4726"
],
"details": "Flask is a web server gateway interface (WSGI) web application framework. In versions 3.1.2 and below, when the session object is accessed, Flask should set the Vary: Cookie header., resulting in a Use of Cache Containing Sensitive Information vulnerability. The logic instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked. The severity and risk depend on the application being hosted behind a caching proxy that doesn\u0027t ignore responses with cookies, not setting a Cache-Control header to mark pages as private or non-cacheable, and accessing the session in a way that only touches keys without reading values or mutating the session. The issue has been fixed in version 3.1.3.",
"id": "PYSEC-2026-2151",
"modified": "2026-07-13T05:48:47.906977Z",
"published": "2026-02-21T06:17:00.910Z",
"references": [
{
"type": "ADVISORY",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
},
{
"type": "ADVISORY",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "FIX",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
}
],
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
]
}
BREW-AWS-SAM-CLI-CVE-202… (GHSA-68RP-WP8R-4726)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:37 – Updated: 2026-09-17 19:54 – Source website
VLAI
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details
When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.
The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.
- The application must be hosted behind a caching proxy that does not ignore responses with cookies.
- The application does not set a
Cache-Controlheader to indicate that a page is private or should not be cached. - The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Severity
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "flask",
"resource_purl": "pkg:pypi/flask@3.1.3",
"upstream_fixed_in": "3.1.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "aws-sam-cli",
"purl": "pkg:brew/aws-sam-cli"
},
"ranges": [
{
"events": [
{
"introduced": "1.70.0"
},
{
"fixed": "1.155.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/flask@3.1.3",
"name": "flask",
"resource": "flask",
"strategy": "registry",
"subject_version": "3.1.3"
}
]
},
"details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
"id": "BREW-aws-sam-cli-CVE-2026-27205",
"modified": "2026-09-17T19:54:58Z",
"published": "2026-08-13T16:37:01Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/pallets/flask"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways",
"upstream": [
"GHSA-68rp-wp8r-4726",
"CVE-2026-27205",
"PYSEC-2026-2151"
]
}
BREW-BACKGROUNDREMOVER-C… (GHSA-68RP-WP8R-4726)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:37 – Updated: 2026-09-17 17:43 – Source website
VLAI
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details
When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.
The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.
- The application must be hosted behind a caching proxy that does not ignore responses with cookies.
- The application does not set a
Cache-Controlheader to indicate that a page is private or should not be cached. - The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Severity
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "flask",
"resource_purl": "pkg:pypi/flask@3.1.3",
"upstream_fixed_in": "3.1.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "backgroundremover",
"purl": "pkg:brew/backgroundremover"
},
"ranges": [
{
"events": [
{
"introduced": "0.3.7"
},
{
"fixed": "0.4.1_1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/flask@3.1.3",
"name": "flask",
"resource": "flask",
"strategy": "registry",
"subject_version": "3.1.3"
}
]
},
"details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
"id": "BREW-backgroundremover-CVE-2026-27205",
"modified": "2026-09-17T17:43:17Z",
"published": "2026-08-13T16:37:03Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/pallets/flask"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways",
"upstream": [
"GHSA-68rp-wp8r-4726",
"CVE-2026-27205",
"PYSEC-2026-2151"
]
}
BREW-BUKU-CVE-2026-27205 (GHSA-68RP-WP8R-4726)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:38 – Updated: 2026-09-17 17:30 – Source website
VLAI
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details
When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.
The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.
- The application must be hosted behind a caching proxy that does not ignore responses with cookies.
- The application does not set a
Cache-Controlheader to indicate that a page is private or should not be cached. - The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Severity
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "flask",
"resource_purl": "pkg:pypi/flask@3.1.3",
"upstream_fixed_in": "3.1.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "buku",
"purl": "pkg:brew/buku"
},
"ranges": [
{
"events": [
{
"introduced": "4.5_1"
},
{
"fixed": "5.1_3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/flask@3.1.3",
"name": "flask",
"resource": "flask",
"strategy": "registry",
"subject_version": "3.1.3"
}
]
},
"details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
"id": "BREW-buku-CVE-2026-27205",
"modified": "2026-09-17T17:30:49Z",
"published": "2026-08-13T16:38:25Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/pallets/flask"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways",
"upstream": [
"GHSA-68rp-wp8r-4726",
"CVE-2026-27205",
"PYSEC-2026-2151"
]
}
BREW-CERTSYNC-CVE-2026-27205 (GHSA-68RP-WP8R-4726)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:39 – Updated: 2026-09-17 19:49 – Source website
VLAI
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details
When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.
The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.
- The application must be hosted behind a caching proxy that does not ignore responses with cookies.
- The application does not set a
Cache-Controlheader to indicate that a page is private or should not be cached. - The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Severity
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "flask",
"resource_purl": "pkg:pypi/flask@3.1.3",
"upstream_fixed_in": "3.1.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "certsync",
"purl": "pkg:brew/certsync"
},
"ranges": [
{
"events": [
{
"introduced": "0.1.4"
},
{
"fixed": "0.1.6_6"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/flask@3.1.3",
"name": "flask",
"resource": "flask",
"strategy": "registry",
"subject_version": "3.1.3"
}
]
},
"details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
"id": "BREW-certsync-CVE-2026-27205",
"modified": "2026-09-17T19:49:46Z",
"published": "2026-08-13T16:39:03Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/pallets/flask"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways",
"upstream": [
"GHSA-68rp-wp8r-4726",
"CVE-2026-27205",
"PYSEC-2026-2151"
]
}
BREW-FAVA-CVE-2026-27205 (GHSA-68RP-WP8R-4726)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:46 – Updated: 2026-09-17 18:01 – Source website
VLAI
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details
When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.
The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.
- The application must be hosted behind a caching proxy that does not ignore responses with cookies.
- The application does not set a
Cache-Controlheader to indicate that a page is private or should not be cached. - The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Severity
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "flask",
"resource_purl": "pkg:pypi/flask@3.1.3",
"upstream_fixed_in": "3.1.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "fava",
"purl": "pkg:brew/fava"
},
"ranges": [
{
"events": [
{
"introduced": "1.14"
},
{
"fixed": "1.30.12_1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/flask@3.1.3",
"name": "flask",
"resource": "flask",
"strategy": "registry",
"subject_version": "3.1.3"
}
]
},
"details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
"id": "BREW-fava-CVE-2026-27205",
"modified": "2026-09-17T18:01:22Z",
"published": "2026-08-13T16:46:31Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/pallets/flask"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways",
"upstream": [
"GHSA-68rp-wp8r-4726",
"CVE-2026-27205",
"PYSEC-2026-2151"
]
}
BREW-FLEXGET-CVE-2026-27205 (GHSA-68RP-WP8R-4726)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:47 – Updated: 2026-09-17 19:40 – Source website
VLAI
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details
When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.
The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.
- The application must be hosted behind a caching proxy that does not ignore responses with cookies.
- The application does not set a
Cache-Controlheader to indicate that a page is private or should not be cached. - The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Severity
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "flask",
"resource_purl": "pkg:pypi/flask@3.1.3",
"upstream_fixed_in": "3.1.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "flexget",
"purl": "pkg:brew/flexget"
},
"ranges": [
{
"events": [
{
"introduced": "3.17.7"
},
{
"fixed": "3.18.49"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/flask@3.1.3",
"name": "flask",
"resource": "flask",
"strategy": "registry",
"subject_version": "3.1.3"
}
]
},
"details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
"id": "BREW-flexget-CVE-2026-27205",
"modified": "2026-09-17T19:40:23Z",
"published": "2026-08-13T16:47:29Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/pallets/flask"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways",
"upstream": [
"GHSA-68rp-wp8r-4726",
"CVE-2026-27205",
"PYSEC-2026-2151"
]
}
BREW-GDBGUI-CVE-2026-27205 (GHSA-68RP-WP8R-4726)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:49 – Updated: 2026-09-09 23:59 – Source website
VLAI
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details
When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.
The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.
- The application must be hosted behind a caching proxy that does not ignore responses with cookies.
- The application does not set a
Cache-Controlheader to indicate that a page is private or should not be cached. - The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Severity
{
"affected": [
{
"ecosystem_specific": {
"fix": null,
"range_state": "affected",
"resource": "flask",
"resource_purl": "pkg:pypi/flask@3.1.1",
"upstream_fixed_in": "3.1.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "gdbgui",
"purl": "pkg:brew/gdbgui"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/flask@3.1.1",
"name": "flask",
"resource": "flask",
"strategy": "registry",
"subject_version": "3.1.1"
}
]
},
"details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
"id": "BREW-gdbgui-CVE-2026-27205",
"modified": "2026-09-09T23:59:59Z",
"published": "2026-08-13T16:49:15Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/pallets/flask"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways",
"upstream": [
"GHSA-68rp-wp8r-4726",
"CVE-2026-27205",
"PYSEC-2026-2151"
]
}
BREW-GRIP-CVE-2026-27205 (GHSA-68RP-WP8R-4726)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:55 – Updated: 2026-09-10 00:06 – Source website
VLAI
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details
When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.
The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.
- The application must be hosted behind a caching proxy that does not ignore responses with cookies.
- The application does not set a
Cache-Controlheader to indicate that a page is private or should not be cached. - The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Severity
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "flask",
"resource_purl": "pkg:pypi/flask@3.1.3",
"upstream_fixed_in": "3.1.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "grip",
"purl": "pkg:brew/grip"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.6.2_21"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/flask@3.1.3",
"name": "flask",
"resource": "flask",
"strategy": "registry",
"subject_version": "3.1.3"
}
]
},
"details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
"id": "BREW-grip-CVE-2026-27205",
"modified": "2026-09-10T00:06:27Z",
"published": "2026-08-13T16:55:20Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/pallets/flask"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways",
"upstream": [
"GHSA-68rp-wp8r-4726",
"CVE-2026-27205",
"PYSEC-2026-2151"
]
}
BREW-ICLOUDPD-CVE-2026-27205 (GHSA-68RP-WP8R-4726)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:59 – Updated: 2026-09-10 00:11 – Source website
VLAI
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details
When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.
The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.
- The application must be hosted behind a caching proxy that does not ignore responses with cookies.
- The application does not set a
Cache-Controlheader to indicate that a page is private or should not be cached. - The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Severity
{
"affected": [
{
"ecosystem_specific": {
"fix": null,
"range_state": "affected",
"resource": "flask",
"resource_purl": "pkg:pypi/flask@3.1.1",
"upstream_fixed_in": "3.1.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "icloudpd",
"purl": "pkg:brew/icloudpd"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/flask@3.1.1",
"name": "flask",
"resource": "flask",
"strategy": "registry",
"subject_version": "3.1.1"
}
]
},
"details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
"id": "BREW-icloudpd-CVE-2026-27205",
"modified": "2026-09-10T00:11:17Z",
"published": "2026-08-13T16:59:03Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/pallets/flask"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways",
"upstream": [
"GHSA-68rp-wp8r-4726",
"CVE-2026-27205",
"PYSEC-2026-2151"
]
}
BREW-KEEPER-COMMANDER-CV… (GHSA-68RP-WP8R-4726)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:01 – Updated: 2026-09-17 18:04 – Source website
VLAI
Summary
Flask session does not add `Vary: Cookie` header when accessed in some ways
Details
When the session object is accessed, Flask should set the Vary: Cookie header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python in operator were overlooked.
The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met.
- The application must be hosted behind a caching proxy that does not ignore responses with cookies.
- The application does not set a
Cache-Controlheader to indicate that a page is private or should not be cached. - The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.
Severity
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "flask",
"resource_purl": "pkg:pypi/flask@3.1.3",
"upstream_fixed_in": "3.1.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "keeper-commander",
"purl": "pkg:brew/keeper-commander"
},
"ranges": [
{
"events": [
{
"introduced": "17.0.20"
},
{
"fixed": "17.2.8"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/flask@3.1.3",
"name": "flask",
"resource": "flask",
"strategy": "registry",
"subject_version": "3.1.3"
}
]
},
"details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
"id": "BREW-keeper-commander-CVE-2026-27205",
"modified": "2026-09-17T18:04:36Z",
"published": "2026-08-13T17:01:22Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
},
{
"type": "PACKAGE",
"url": "https://github.com/pallets/flask"
},
{
"type": "WEB",
"url": "https://github.com/pallets/flask/releases/tag/3.1.3"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways",
"upstream": [
"GHSA-68rp-wp8r-4726",
"CVE-2026-27205",
"PYSEC-2026-2151"
]
}
Loading…
Trend slope:
-
(linear fit over daily sighting counts)
Show additional events:
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
Loading…
Loading…