CWE-295
AllowedImproper Certificate Validation
Abstraction: Base · Status: Draft
The product does not validate, or incorrectly validates, a certificate.
2267 vulnerabilities reference this CWE, most recent first.
GHSA-PGQV-97HH-8VV7
Vulnerability from github – Published: 2024-10-31 09:30 – Updated: 2024-10-31 09:30HCL AppScan Source <= 10.6.0 does not properly validate a TLS/SSL certificate for an executable.
{
"affected": [],
"aliases": [
"CVE-2024-30149"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-10-31T09:15:02Z",
"severity": "MODERATE"
},
"details": "HCL AppScan Source \u003c= 10.6.0 does not properly validate a TLS/SSL certificate for an executable.",
"id": "GHSA-pgqv-97hh-8vv7",
"modified": "2024-10-31T09:30:42Z",
"published": "2024-10-31T09:30:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-30149"
},
{
"type": "WEB",
"url": "https://support.hcl-software.com/csm?id=kb_article\u0026sysparm_article=KB0116990"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-PGW7-WX7W-2W33
Vulnerability from github – Published: 2022-06-17 01:02 – Updated: 2022-07-29 18:13Description
Undici.ProxyAgent never verifies the remote server's certificate, and always exposes all request & response data to the proxy. This unexpectedly means that proxies can MitM all HTTPS traffic, and if the proxy's URL is HTTP then it also means that nominally HTTPS requests are actually sent via plain-text HTTP between Undici and the proxy server.
Impact
This affects all use of HTTPS via HTTP proxy using Undici.ProxyAgent with Undici or Node's global fetch. In this case, it removes all HTTPS security from all requests sent using Undici's ProxyAgent, allowing trivial MitM attacks by anybody on the network path between the client and the target server (local network users, your ISP, the proxy, the target server's ISP, etc).
This less seriously affects HTTPS via HTTPS proxies. When you send HTTPS via a proxy to a remote server, the proxy can freely view or modify all HTTPS traffic unexpectedly (but only the proxy).
Patches
This issue was patched in Undici v5.5.1.
Workarounds
At the time of writing, the only workaround is to not use ProxyAgent as a dispatcher for TLS Connections.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 5.5.0"
},
"package": {
"ecosystem": "npm",
"name": "undici"
},
"ranges": [
{
"events": [
{
"introduced": "4.8.2"
},
{
"fixed": "5.5.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2022-32210"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": true,
"github_reviewed_at": "2022-06-17T01:02:29Z",
"nvd_published_at": "2022-07-14T15:15:00Z",
"severity": "HIGH"
},
"details": "### Description\n\n`Undici.ProxyAgent` never verifies the remote server\u0027s certificate, and always exposes all request \u0026 response data to the proxy. This unexpectedly means that proxies can MitM all HTTPS traffic, and if the proxy\u0027s URL is HTTP then it also means that nominally HTTPS requests are actually sent via plain-text HTTP between Undici and the proxy server.\n\n### Impact\n\nThis affects all use of HTTPS via HTTP proxy using **`Undici.ProxyAgent`** with Undici or Node\u0027s global `fetch`. In this case, it removes all HTTPS security from all requests sent using Undici\u0027s `ProxyAgent`, allowing trivial MitM attacks by anybody on the network path between the client and the target server (local network users, your ISP, the proxy, the target server\u0027s ISP, etc).\nThis less seriously affects HTTPS via HTTPS proxies. When you send HTTPS via a proxy to a remote server, the proxy can freely view or modify all HTTPS traffic unexpectedly (but only the proxy). \n\n### Patches\n\nThis issue was patched in Undici v5.5.1.\n\n### Workarounds\n\nAt the time of writing, the only workaround is to not use `ProxyAgent` as a dispatcher for TLS Connections.",
"id": "GHSA-pgw7-wx7w-2w33",
"modified": "2022-07-29T18:13:25Z",
"published": "2022-06-17T01:02:29Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nodejs/undici/security/advisories/GHSA-pgw7-wx7w-2w33"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-32210"
},
{
"type": "WEB",
"url": "https://hackerone.com/reports/1583680"
},
{
"type": "PACKAGE",
"url": "https://github.com/nodejs/undici"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "ProxyAgent vulnerable to MITM"
}
GHSA-PH5J-38MG-J6HP
Vulnerability from github – Published: 2026-03-07 00:30 – Updated: 2026-03-10 18:31Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS.
{
"affected": [],
"aliases": [
"CVE-2026-27138"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-06T22:16:00Z",
"severity": "MODERATE"
},
"details": "Certificate verification can panic when a certificate in the chain has an empty DNS name and another certificate in the chain has excluded name constraints. This can crash programs that are either directly verifying X.509 certificate chains, or those that use TLS.",
"id": "GHSA-ph5j-38mg-j6hp",
"modified": "2026-03-10T18:31:14Z",
"published": "2026-03-07T00:30:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27138"
},
{
"type": "WEB",
"url": "https://go.dev/cl/752183"
},
{
"type": "WEB",
"url": "https://go.dev/issue/77953"
},
{
"type": "WEB",
"url": "https://groups.google.com/g/golang-announce/c/EdhZqrQ98hk"
},
{
"type": "WEB",
"url": "https://pkg.go.dev/vuln/GO-2026-4600"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
GHSA-PHQH-XP3P-H6MR
Vulnerability from github – Published: 2026-10-05 00:30 – Updated: 2026-10-05 00:30The gist RubyGem before 6.1.0 contains an improper certificate validation vulnerability that allows on-path attackers to intercept HTTPS traffic because http_connection in lib/gist.rb sets VERIFY_NONE. Attackers can present any certificate to read or modify GitHub API traffic, stealing OAuth tokens and login credentials to read and modify the victim's gists.
{
"affected": [],
"aliases": [
"CVE-2026-105221"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-04T23:16:59Z",
"severity": "CRITICAL"
},
"details": "The gist RubyGem before 6.1.0 contains an improper certificate validation vulnerability that allows on-path attackers to intercept HTTPS traffic because http_connection in lib/gist.rb sets VERIFY_NONE. Attackers can present any certificate to read or modify GitHub API traffic, stealing OAuth tokens and login credentials to read and modify the victim\u0027s gists.",
"id": "GHSA-phqh-xp3p-h6mr",
"modified": "2026-10-05T00:30:25Z",
"published": "2026-10-05T00:30:25Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-105221"
},
{
"type": "WEB",
"url": "https://github.com/defunkt/gist/issues/373"
},
{
"type": "WEB",
"url": "https://github.com/defunkt/gist/commit/07ccc1a6d46e9d36f0e85d0b1c5d795890ae6bcf"
},
{
"type": "WEB",
"url": "https://github.com/defunkt/gist"
},
{
"type": "WEB",
"url": "https://github.com/defunkt/gist/blob/v6.0.0/lib/gist.rb#L466-L468"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/gist-rubygem-before-6.1.0-disabled-tls-certificate-verification"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
GHSA-PHVV-C9GW-V54H
Vulnerability from github – Published: 2022-05-13 01:47 – Updated: 2022-05-13 01:47LibreSSL 2.5.1 to 2.5.3 lacks TLS certificate verification if SSL_get_verify_result is relied upon for a later check of a verification result, in a use case where a user-provided verification callback returns 1, as demonstrated by acceptance of invalid certificates by nginx.
{
"affected": [],
"aliases": [
"CVE-2017-8301"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2017-04-27T17:59:00Z",
"severity": "MODERATE"
},
"details": "LibreSSL 2.5.1 to 2.5.3 lacks TLS certificate verification if SSL_get_verify_result is relied upon for a later check of a verification result, in a use case where a user-provided verification callback returns 1, as demonstrated by acceptance of invalid certificates by nginx.",
"id": "GHSA-phvv-c9gw-v54h",
"modified": "2022-05-13T01:47:28Z",
"published": "2022-05-13T01:47:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2017-8301"
},
{
"type": "WEB",
"url": "https://github.com/libressl-portable/portable/issues/307"
},
{
"type": "WEB",
"url": "https://trac.nginx.org/nginx/ticket/1257"
},
{
"type": "WEB",
"url": "http://seclists.org/oss-sec/2017/q2/145"
},
{
"type": "WEB",
"url": "http://www.securityfocus.com/bid/98076"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-PJFQ-H6GX-WRCF
Vulnerability from github – Published: 2023-08-23 18:30 – Updated: 2025-02-13 18:31If the MongoDB Server running on Windows or macOS is configured to use TLS with a specific set of configuration options that are already known to work securely in other platforms (e.g. Linux), it is possible that client certificate validation may not be in effect, potentially allowing client to establish a TLS connection with the server that supplies any certificate.
This issue affect all MongoDB Server v6.3 versions, MongoDB Server v5.0 versions v5.0.0 to v5.0.14 and all MongoDB Server v4.4 versions.
{
"affected": [],
"aliases": [
"CVE-2023-1409"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2023-08-23T16:15:08Z",
"severity": "HIGH"
},
"details": "If the MongoDB Server running on Windows or macOS is configured to use TLS with a specific set of configuration options that are already known to work securely in other platforms (e.g. Linux), it is possible that client certificate validation may not be in effect, potentially allowing client to establish a TLS connection with the server that supplies any certificate.\n\nThis issue affect all MongoDB Server v6.3 versions, MongoDB Server v5.0 versions v5.0.0 to v5.0.14 and all MongoDB Server v4.4 versions.",
"id": "GHSA-pjfq-h6gx-wrcf",
"modified": "2025-02-13T18:31:49Z",
"published": "2023-08-23T18:30:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2023-1409"
},
{
"type": "WEB",
"url": "https://jira.mongodb.org/browse/SERVER-73662"
},
{
"type": "WEB",
"url": "https://jira.mongodb.org/browse/SERVER-77028"
},
{
"type": "WEB",
"url": "https://security.netapp.com/advisory/ntap-20230921-0007"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-PM34-H6P9-7P29
Vulnerability from github – Published: 2026-08-19 15:32 – Updated: 2026-08-19 15:32IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 NIM could allow a remote attacker to gain unauthorized access to AIX systems due to improper validation of TLS certificates.
{
"affected": [],
"aliases": [
"CVE-2026-15078"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-19T15:16:56Z",
"severity": "HIGH"
},
"details": "IBM AIX 7.2, and 7.3 and IBM PowerVM VIOS 4.1 NIM could allow a remote attacker to gain unauthorized access to AIX systems due to improper validation of TLS certificates.",
"id": "GHSA-pm34-h6p9-7p29",
"modified": "2026-08-19T15:32:37Z",
"published": "2026-08-19T15:32:37Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-15078"
},
{
"type": "WEB",
"url": "https://www.ibm.com/support/pages/node/7283858"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-PM3J-6F7C-8V2Q
Vulnerability from github – Published: 2025-01-10 18:31 – Updated: 2025-01-13 21:30Improper handling and storage of certificates in CP Plus CP-VNR-3104 B3223P22C02424 allow attackers to decrypt communications or execute a man-in-the-middle attacks.
{
"affected": [],
"aliases": [
"CVE-2024-54848"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-01-10T17:15:17Z",
"severity": "HIGH"
},
"details": "Improper handling and storage of certificates in CP Plus CP-VNR-3104 B3223P22C02424 allow attackers to decrypt communications or execute a man-in-the-middle attacks.",
"id": "GHSA-pm3j-6f7c-8v2q",
"modified": "2025-01-13T21:30:52Z",
"published": "2025-01-10T18:31:41Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-21551"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-54848"
},
{
"type": "WEB",
"url": "https://capec.mitre.org/data/definitions/233"
},
{
"type": "WEB",
"url": "https://github.com/Yashodhanvivek/CP-VNR-3104-NVR-Vulnerabilties/blob/main/CPPlus_CP-VNR-3104_Security_Assessment.pdf"
},
{
"type": "WEB",
"url": "https://payatu.com/blog/solving-the-problem-of-encrypted-firmware"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N",
"type": "CVSS_V3"
}
]
}
GHSA-PM77-C4Q7-3FWJ
Vulnerability from github – Published: 2021-10-12 16:31 – Updated: 2021-10-08 22:58Gateways/Gateway.php in Heartland & Global Payments PHP SDK before 2.0.0 does not enforce SSL certificate validations.
{
"affected": [
{
"package": {
"ecosystem": "Packagist",
"name": "globalpayments/php-sdk"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2019-20455"
],
"database_specific": {
"cwe_ids": [
"CWE-295"
],
"github_reviewed": true,
"github_reviewed_at": "2021-10-08T22:58:55Z",
"nvd_published_at": "2020-02-14T16:15:00Z",
"severity": "MODERATE"
},
"details": "Gateways/Gateway.php in Heartland \u0026 Global Payments PHP SDK before 2.0.0 does not enforce SSL certificate validations.",
"id": "GHSA-pm77-c4q7-3fwj",
"modified": "2021-10-08T22:58:55Z",
"published": "2021-10-12T16:31:12Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2019-20455"
},
{
"type": "WEB",
"url": "https://github.com/globalpayments/php-sdk/pull/8"
},
{
"type": "WEB",
"url": "https://github.com/globalpayments/php-sdk/pull/8/commits/c86e18f28c5eba0d6ede7d557756d978ea83d3c9"
},
{
"type": "PACKAGE",
"url": "https://github.com/globalpayments/php-sdk"
},
{
"type": "WEB",
"url": "https://github.com/globalpayments/php-sdk/compare/1.3.3...2.0.0"
},
{
"type": "WEB",
"url": "https://github.com/globalpayments/php-sdk/releases/tag/2.0.0"
},
{
"type": "WEB",
"url": "https://winterdragon.ca/global-payments-vulnerability"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Improper Certificate Validation in Heartland \u0026 Global Payments PHP SDK"
}
GHSA-PM7C-VG9H-JXXC
Vulnerability from github – Published: 2022-05-02 03:35 – Updated: 2024-02-14 18:30Mozilla Network Security Services (NSS) before 3.12.3, Firefox before 3.0.13, Thunderbird before 2.0.0.23, and SeaMonkey before 1.1.18 do not properly handle a '\0' character in a domain name in the subject's Common Name (CN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority. NOTE: this was originally reported for Firefox before 3.5.
{
"affected": [],
"aliases": [
"CVE-2009-2408"
],
"database_specific": {
"cwe_ids": [
"CWE-20",
"CWE-295"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2009-07-30T19:30:00Z",
"severity": "MODERATE"
},
"details": "Mozilla Network Security Services (NSS) before 3.12.3, Firefox before 3.0.13, Thunderbird before 2.0.0.23, and SeaMonkey before 1.1.18 do not properly handle a \u0027\\0\u0027 character in a domain name in the subject\u0027s Common Name (CN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority. NOTE: this was originally reported for Firefox before 3.5.",
"id": "GHSA-pm7c-vg9h-jxxc",
"modified": "2024-02-14T18:30:24Z",
"published": "2022-05-02T03:35:01Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2009-2408"
},
{
"type": "WEB",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=510251"
},
{
"type": "WEB",
"url": "https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A10751"
},
{
"type": "WEB",
"url": "https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A8458"
},
{
"type": "WEB",
"url": "https://usn.ubuntu.com/810-2"
},
{
"type": "WEB",
"url": "http://isc.sans.org/diary.html?storyid=7003"
},
{
"type": "WEB",
"url": "http://lists.opensuse.org/opensuse-security-announce/2009-11/msg00004.html"
},
{
"type": "WEB",
"url": "http://marc.info/?l=oss-security\u0026m=125198917018936\u0026w=2"
},
{
"type": "WEB",
"url": "http://osvdb.org/56723"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/36088"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/36125"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/36139"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/36157"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/36434"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/36669"
},
{
"type": "WEB",
"url": "http://secunia.com/advisories/37098"
},
{
"type": "WEB",
"url": "http://sunsolve.sun.com/search/document.do?assetkey=1-77-1021030.1-1"
},
{
"type": "WEB",
"url": "http://www.debian.org/security/2009/dsa-1874"
},
{
"type": "WEB",
"url": "http://www.mandriva.com/security/advisories?name=MDVSA-2009:197"
},
{
"type": "WEB",
"url": "http://www.mandriva.com/security/advisories?name=MDVSA-2009:216"
},
{
"type": "WEB",
"url": "http://www.mandriva.com/security/advisories?name=MDVSA-2009:217"
},
{
"type": "WEB",
"url": "http://www.mozilla.org/security/announce/2009/mfsa2009-42.html"
},
{
"type": "WEB",
"url": "http://www.novell.com/linux/security/advisories/2009_48_firefox.html"
},
{
"type": "WEB",
"url": "http://www.openldap.org/devel/cvsweb.cgi/libraries/libldap/tls_m.c.diff?r1=1.8\u0026r2=1.11\u0026f=h"
},
{
"type": "WEB",
"url": "http://www.redhat.com/support/errata/RHSA-2009-1207.html"
},
{
"type": "WEB",
"url": "http://www.redhat.com/support/errata/RHSA-2009-1432.html"
},
{
"type": "WEB",
"url": "http://www.securitytracker.com/id?1022632"
},
{
"type": "WEB",
"url": "http://www.ubuntu.com/usn/usn-810-1"
},
{
"type": "WEB",
"url": "http://www.vupen.com/english/advisories/2009/2085"
},
{
"type": "WEB",
"url": "http://www.vupen.com/english/advisories/2009/3184"
},
{
"type": "WEB",
"url": "http://www.wired.com/threatlevel/2009/07/kaminsky"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
]
}
Mitigation
Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
Mitigation
If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.
CAPEC-459: Creating a Rogue Certification Authority Certificate
An adversary exploits a weakness resulting from using a hashing algorithm with weak collision resistance to generate certificate signing requests (CSR) that contain collision blocks in their "to be signed" parts. The adversary submits one CSR to be signed by a trusted certificate authority then uses the signed blob to make a second certificate appear signed by said certificate authority. Due to the hash collision, both certificates, though different, hash to the same value and so the signed blob works just as well in the second certificate. The net effect is that the adversary's second X.509 certificate, which the Certification Authority has never seen, is now signed and validated by that Certification Authority.
CAPEC-475: Signature Spoofing by Improper Validation
An adversary exploits a cryptographic weakness in the signature verification algorithm implementation to generate a valid signature without knowing the key.