CWE-327
Allowed-with-ReviewUse of a Broken or Risky Cryptographic Algorithm
Abstraction: Class · Status: Draft
The product uses a broken or risky cryptographic algorithm or protocol.
1020 vulnerabilities reference this CWE, most recent first.
GHSA-VQWP-45WM-R9R5
Vulnerability from github – Published: 2026-06-04 12:30 – Updated: 2026-07-15 21:49A vulnerability has been found in Streamlit up to 1.53.0. Impacted is an unknown function in the library lib/streamlit/runtime/caching/hashing.py of the component Palette Handler. Such manipulation leads to use of weak hash. Local access is required to approach this attack. The attack requires a high level of complexity. The exploitability is considered difficult. The exploit has been disclosed to the public and may be used. The pull request to fix this issue awaits acceptance.
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "streamlit"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "1.53.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-10804"
],
"database_specific": {
"cwe_ids": [
"CWE-327"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-15T21:49:13Z",
"nvd_published_at": "2026-06-04T12:16:24Z",
"severity": "LOW"
},
"details": "A vulnerability has been found in Streamlit up to 1.53.0. Impacted is an unknown function in the library lib/streamlit/runtime/caching/hashing.py of the component Palette Handler. Such manipulation leads to use of weak hash. Local access is required to approach this attack. The attack requires a high level of complexity. The exploitability is considered difficult. The exploit has been disclosed to the public and may be used. The pull request to fix this issue awaits acceptance.",
"id": "GHSA-vqwp-45wm-r9r5",
"modified": "2026-07-15T21:49:13Z",
"published": "2026-06-04T12:30:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-10804"
},
{
"type": "WEB",
"url": "https://github.com/streamlit/streamlit/issues/14622"
},
{
"type": "WEB",
"url": "https://github.com/streamlit/streamlit/pull/14635"
},
{
"type": "WEB",
"url": "https://github.com/streamlit/streamlit/pull/15397"
},
{
"type": "WEB",
"url": "https://github.com/streamlit/streamlit/commit/fec0f584dae9261abed16cad35b32922104bb933"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/streamlit/PYSEC-2026-212.yaml"
},
{
"type": "PACKAGE",
"url": "https://github.com/streamlit/streamlit"
},
{
"type": "WEB",
"url": "https://vuldb.com/cve/CVE-2026-10804"
},
{
"type": "WEB",
"url": "https://vuldb.com/submit/831508"
},
{
"type": "WEB",
"url": "https://vuldb.com/vuln/368253"
},
{
"type": "WEB",
"url": "https://vuldb.com/vuln/368253/cti"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:L",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:P",
"type": "CVSS_V4"
}
],
"summary": "Streamlit @st.cache_data hash collision via fixed sampling seed and PIL P-mode palette omission"
}
GHSA-VVWM-GCGM-H9J6
Vulnerability from github – Published: 2022-01-22 00:00 – Updated: 2022-01-28 00:03Fresenius Kabi Vigilant Software Suite (Mastermed Dashboard) version 2.0.1.3 issues authentication tokens to authenticated users that are signed with a symmetric encryption key. An attacker in possession of the key can issue valid JWTs and impersonate arbitrary users.
{
"affected": [],
"aliases": [
"CVE-2021-33846"
],
"database_specific": {
"cwe_ids": [
"CWE-327"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-01-21T19:15:00Z",
"severity": "HIGH"
},
"details": "Fresenius Kabi Vigilant Software Suite (Mastermed Dashboard) version 2.0.1.3 issues authentication tokens to authenticated users that are signed with a symmetric encryption key. An attacker in possession of the key can issue valid JWTs and impersonate arbitrary users.",
"id": "GHSA-vvwm-gcgm-h9j6",
"modified": "2022-01-28T00:03:21Z",
"published": "2022-01-22T00:00:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-33846"
},
{
"type": "WEB",
"url": "https://www.cisa.gov/uscert/ics/advisories/icsma-21-355-01"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-VW76-VM27-JX3R
Vulnerability from github – Published: 2022-05-24 17:39 – Updated: 2026-07-05 00:31Bleichenbacher's attack on PKCS #1 v1.5 padding for RSA in Microchip Libraries for Applications 2018-11-26 All up to 2018-11-26. The vulnerability can allow one to use Bleichenbacher's oracle attack to decrypt an encrypted ciphertext by making successive queries to the server using the vulnerable library, resulting in remote information disclosure.
{
"affected": [],
"aliases": [
"CVE-2020-20950"
],
"database_specific": {
"cwe_ids": [
"CWE-326",
"CWE-327"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2021-01-19T13:15:00Z",
"severity": "MODERATE"
},
"details": "Bleichenbacher\u0027s attack on PKCS #1 v1.5 padding for RSA in Microchip Libraries for Applications 2018-11-26 All up to 2018-11-26. The vulnerability can allow one to use Bleichenbacher\u0027s oracle attack to decrypt an encrypted ciphertext by making successive queries to the server using the vulnerable library, resulting in remote information disclosure.",
"id": "GHSA-vw76-vm27-jx3r",
"modified": "2026-07-05T00:31:17Z",
"published": "2022-05-24T17:39:26Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2020-20950"
},
{
"type": "WEB",
"url": "https://bi-zone.medium.com/silence-will-fall-or-how-it-can-take-2-years-to-get-your-vuln-registered-e6134846f5bb"
},
{
"type": "WEB",
"url": "https://www.microchip.com/mplab/microchip-libraries-for-applications"
},
{
"type": "WEB",
"url": "http://archiv.infsec.ethz.ch/education/fs08/secsem/bleichenbacher98.pdf"
},
{
"type": "WEB",
"url": "http://microchip.com"
}
],
"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"
}
]
}
GHSA-VWJ8-79VF-V875
Vulnerability from github – Published: 2026-02-09 06:30 – Updated: 2026-03-06 21:30A vulnerability has been found in FAST/TOOLS provided by Yokogawa Electric Corporation.
This product supports old SSL/TLS versions, potentially allowing an attacker to decrypt communications with the web server.
The affected products and versions are as follows: FAST/TOOLS (Packages: RVSVRN, UNSVRN, HMIWEB, FTEES, HMIMOB) R9.01 to R10.04
{
"affected": [],
"aliases": [
"CVE-2025-66598"
],
"database_specific": {
"cwe_ids": [
"CWE-327"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-02-09T05:16:24Z",
"severity": "HIGH"
},
"details": "A vulnerability has been found in FAST/TOOLS provided by Yokogawa Electric Corporation.\n\n\n\nThis product supports\nold SSL/TLS versions, potentially allowing an attacker to decrypt\ncommunications with the web server.\n\n\n\nThe\naffected products and versions are as follows: FAST/TOOLS (Packages: RVSVRN, UNSVRN, HMIWEB, FTEES, HMIMOB) R9.01 to\nR10.04",
"id": "GHSA-vwj8-79vf-v875",
"modified": "2026-03-06T21:30:31Z",
"published": "2026-02-09T06:30:28Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-66598"
},
{
"type": "WEB",
"url": "https://web-material3.yokogawa.com/1/39206/files/YSAR-26-0001-E.pdf"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/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-VX8C-PPGJ-6WG7
Vulnerability from github – Published: 2022-01-22 00:00 – Updated: 2022-01-29 00:01The SSL/TLS configuration of Fresenius Kabi Agilia Link + version 3.0 has serious deficiencies that may allow an attacker to compromise SSL/TLS sessions in different ways. An attacker may be able to eavesdrop on transferred data, manipulate data allegedly secured by SSL/TLS, and impersonate an entity to gain access to sensitive information.
{
"affected": [],
"aliases": [
"CVE-2021-31562"
],
"database_specific": {
"cwe_ids": [
"CWE-327"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2022-01-21T19:15:00Z",
"severity": "CRITICAL"
},
"details": "The SSL/TLS configuration of Fresenius Kabi Agilia Link + version 3.0 has serious deficiencies that may allow an attacker to compromise SSL/TLS sessions in different ways. An attacker may be able to eavesdrop on transferred data, manipulate data allegedly secured by SSL/TLS, and impersonate an entity to gain access to sensitive information.",
"id": "GHSA-vx8c-ppgj-6wg7",
"modified": "2022-01-29T00:01:10Z",
"published": "2022-01-22T00:00:34Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-31562"
},
{
"type": "WEB",
"url": "https://www.cisa.gov/uscert/ics/advisories/icsma-21-355-01"
}
],
"schema_version": "1.4.0",
"severity": []
}
GHSA-VX8M-7CR4-H238
Vulnerability from github – Published: 2024-05-14 18:30 – Updated: 2024-05-14 18:30Dell PowerScale OneFS versions 8.2.x through 9.7.0.2 contains a use of a broken or risky cryptographic algorithm vulnerability. A remote unauthenticated attacker could potentially exploit this vulnerability, leading to information disclosure.
{
"affected": [],
"aliases": [
"CVE-2024-25968"
],
"database_specific": {
"cwe_ids": [
"CWE-327"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-14T16:16:18Z",
"severity": "MODERATE"
},
"details": "Dell PowerScale OneFS versions 8.2.x through 9.7.0.2 contains a use of a broken or risky cryptographic algorithm vulnerability. A remote unauthenticated attacker could potentially exploit this vulnerability, leading to information disclosure.",
"id": "GHSA-vx8m-7cr4-h238",
"modified": "2024-05-14T18:30:59Z",
"published": "2024-05-14T18:30:59Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-25968"
},
{
"type": "WEB",
"url": "https://www.dell.com/support/kbdoc/en-us/000224860/dsa-2024-163-security-update-for-dell-powerscale-onefs-for-multiple-security-vulnerabilities"
}
],
"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"
}
]
}
GHSA-VXXM-WWQH-MH47
Vulnerability from github – Published: 2026-08-17 21:56 – Updated: 2026-08-17 21:57Impact
An issue in DigestAuthProvider.verify:
Algorithm silently forced to MD5. The configured algorithm parameter was ignored — every verification used MD5 regardless of configuration. Deployments believing they were running SHA-256 Digest auth were silently inheriting MD5's collision weaknesses, including documented attack paths against Digest schemes that rely on the hash being collision-resistant.
Who is affected: any application using http4k-security-digest for HTTP Digest authentication. The bug has been present since DigestAuthProvider was introduced (commit 8a52b615b1, 2021).
Patches
| Line | Fixed in | Edition |
|---|---|---|
| v6.x (Community) | 6.50.0.0 | Community |
| v5.x (LTS) | 5.42.0.0 | Enterprise — contact enterprise@http4k.org (if Digest auth is present in your v5.x line) |
| v4.x (LTS) | 4.51.0.0 | Enterprise — contact enterprise@http4k.org (if Digest auth is present in your v4.x line) |
The fix:
- Hashes with the configured algorithm instead of hardcoded MD5.
Workarounds
For deployments that cannot upgrade immediately:
- Algorithm gap: do not rely on algorithm configuration; assume MD5 is in use and treat the Digest credentials as low-trust.
References
- Vulnerability first present:
8a52b615b1 - Algorithm fix:
65d23d99fc - Fix release: v6.50.0.0
- Background: RFC 7616 — HTTP Digest Access Authentication
{
"affected": [
{
"package": {
"ecosystem": "Maven",
"name": "org.http4k:http4k-security-digest"
},
"ranges": [
{
"events": [
{
"introduced": "6.0.0.0"
},
{
"fixed": "6.50.0.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.http4k:http4k-security-digest"
},
"ranges": [
{
"events": [
{
"introduced": "5.0.0.0"
},
{
"fixed": "5.42.0.0"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"package": {
"ecosystem": "Maven",
"name": "org.http4k:http4k-security-digest"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "4.48.2.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-54147"
],
"database_specific": {
"cwe_ids": [
"CWE-327"
],
"github_reviewed": true,
"github_reviewed_at": "2026-08-17T21:56:58Z",
"nvd_published_at": null,
"severity": "MODERATE"
},
"details": "### Impact\n\nAn issue in `DigestAuthProvider.verify`:\n\n **Algorithm silently forced to MD5.** The configured `algorithm` parameter was ignored \u2014 every verification used MD5 regardless of configuration. Deployments believing they were running SHA-256 Digest auth were silently inheriting MD5\u0027s collision weaknesses, including documented attack paths against Digest schemes that rely on the hash being collision-resistant.\n\n**Who is affected:** any application using `http4k-security-digest` for HTTP Digest authentication. The bug has been present since `DigestAuthProvider` was introduced (commit `8a52b615b1`, 2021).\n\n### Patches\n\n| Line | Fixed in | Edition |\n|------|----------|---------|\n| v6.x (Community) | **6.50.0.0** | Community |\n| v5.x (LTS) | **5.42.0.0** | Enterprise \u2014 contact [enterprise@http4k.org](mailto:enterprise@http4k.org) (if Digest auth is present in your v5.x line) |\n| v4.x (LTS) | **4.51.0.0** | Enterprise \u2014 contact [enterprise@http4k.org](mailto:enterprise@http4k.org) (if Digest auth is present in your v4.x line) |\n\nThe fix:\n- Hashes with the configured `algorithm` instead of hardcoded MD5.\n\n### Workarounds\n\nFor deployments that cannot upgrade immediately:\n- **Algorithm gap:** do not rely on `algorithm` configuration; assume MD5 is in use and treat the Digest credentials as low-trust.\n\n### References\n\n- Vulnerability first present: [`8a52b615b1`](https://github.com/http4k/http4k/commit/8a52b615b1)\n- Algorithm fix: [`65d23d99fc`](https://github.com/http4k/http4k/commit/65d23d99fc)\n- Fix release: [v6.50.0.0](https://github.com/http4k/http4k/releases/tag/6.50.0.0)\n- Background: [RFC 7616 \u2014 HTTP Digest Access Authentication](https://datatracker.ietf.org/doc/html/rfc7616)",
"id": "GHSA-vxxm-wwqh-mh47",
"modified": "2026-08-17T21:57:58Z",
"published": "2026-08-17T21:56:58Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/http4k/http4k/security/advisories/GHSA-vxxm-wwqh-mh47"
},
{
"type": "WEB",
"url": "https://github.com/http4k/http4k/commit/65d23d99fc"
},
{
"type": "PACKAGE",
"url": "https://github.com/http4k/http4k"
},
{
"type": "WEB",
"url": "https://github.com/http4k/http4k/releases/tag/6.50.0.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "http4k: `DigestAuthProvider.verify` ignored configured algorithm and did not bind to request URI"
}
GHSA-W2MR-H878-6344
Vulnerability from github – Published: 2024-12-03 18:31 – Updated: 2024-12-11 03:31IBM Cognos Controller 11.0.0 and 11.0.1 uses weaker than expected cryptographic algorithms that could allow an attacker to decrypt highly sensitive information.
{
"affected": [],
"aliases": [
"CVE-2024-41775"
],
"database_specific": {
"cwe_ids": [
"CWE-327"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-12-03T18:15:13Z",
"severity": "MODERATE"
},
"details": "IBM Cognos Controller 11.0.0 and 11.0.1\u00a0uses weaker than expected cryptographic algorithms that could allow an attacker to decrypt highly sensitive information.",
"id": "GHSA-w2mr-h878-6344",
"modified": "2024-12-11T03:31:58Z",
"published": "2024-12-03T18:31:04Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-41775"
},
{
"type": "WEB",
"url": "https://www.ibm.com/support/pages/node/7177220"
}
],
"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"
}
]
}
GHSA-W3GW-F9WR-G6QX
Vulnerability from github – Published: 2026-06-25 21:31 – Updated: 2026-06-27 21:30Certificate policy and RFC 8446 compliance concerns regarding the continued acceptance of SHA-1/MD5 in certificate processing.
{
"affected": [],
"aliases": [
"CVE-2026-6412"
],
"database_specific": {
"cwe_ids": [
"CWE-327"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-06-25T21:16:27Z",
"severity": "LOW"
},
"details": "Certificate policy and RFC 8446 compliance concerns regarding the continued acceptance of SHA-1/MD5 in certificate processing.",
"id": "GHSA-w3gw-f9wr-g6qx",
"modified": "2026-06-27T21:30:27Z",
"published": "2026-06-25T21:31:32Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-6412"
},
{
"type": "WEB",
"url": "https://github.com/wolfSSL/wolfssl/pull/10222"
},
{
"type": "WEB",
"url": "https://www.wolfssl.com/docs/security-vulnerabilities"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/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:Clear",
"type": "CVSS_V4"
}
]
}
GHSA-W3JG-PJXF-73P4
Vulnerability from github – Published: 2026-09-30 23:26 – Updated: 2026-09-30 23:26Vulnerability
The hybrid ML-KEM 768 + X25519 key exchange implementation in russh/src/kex/hybrid_mlkem.rs does not validate that the remote peer's X25519 public key is not the zero point (all-zero 32-byte value). This allows a remote peer to force the X25519 contribution to the combined shared secret to zero, reducing the hybrid KEX to a single-algorithm exchange.
Affected code at HEAD (v0.62.4, commit 0089c89):
Server-side (server_dh, lines 92-93):
let mut c_pk1 = MontgomeryPoint([0; 32]);
c_pk1.0.copy_from_slice(c_pk1_bytes);
// No zero-point check - proceeds to: let k_cl = s_secret * c_pk1;
Client-side (compute_shared_secret, lines 154-155):
let mut s_pk1 = MontgomeryPoint([0; 32]);
s_pk1.0.copy_from_slice(s_pk1_bytes);
// No zero-point check - proceeds to: let k_cl = x25519_secret * s_pk1;
Root Cause
Commit a7fc1eb (2026-07-22, "fix mpint encoding and validate curve25519 keys") added zero-point validation to the standalone Curve25519 KEX in russh/src/kex/curve25519.rs at two locations:
- server_dh line 77: if client_pubkey.0 == [0u8; 32] { return Err(crate::Error::Kex); }
- compute_shared_secret line 122: if remote_pubkey.0 == [0u8; 32] { return Err(crate::Error::Kex); }
The same X25519 scalar multiplication pattern appears in hybrid_mlkem.rs, but the fix was not applied there.
Proof of Concept
A malicious SSH client negotiating mlkem768x25519-sha256 can send a KEX_HYBRID_INIT message containing a valid ML-KEM 768 encapsulation key followed by 32 zero bytes as the X25519 component.
When the server computes k_cl = s_secret * c_pk1, the result is the zero point regardless of the server's secret scalar. The combined shared secret K = SHA-256(k_pq || k_cl) then depends only on the ML-KEM component. The same attack works in reverse against a client connecting to a malicious server.
The zero X25519 public key passes all existing validation (the length check on line 78 succeeds since 32 bytes is correct). No panic or crash occurs - the exchange completes successfully with a weakened shared secret.
Impact
The purpose of hybrid key exchange is defense-in-depth: if either the classical algorithm (X25519) or the post-quantum algorithm (ML-KEM 768) is broken, the combined secret remains secure. By injecting a zero X25519 public key, an attacker eliminates the classical contribution entirely, reducing security to depend solely on ML-KEM.
This matters in two scenarios: 1. If ML-KEM 768 is later found to have a weakness (the explicit threat model hybrid KEX is designed to mitigate), sessions where the X25519 component was zeroed out lose their fallback protection. 2. An active network attacker who can intercept KEX could downgrade the hybrid exchange to effectively single-algorithm security without either peer detecting it.
The severity is MEDIUM rather than HIGH because the ML-KEM component still provides strong security today, and an active attacker who can modify KEX messages can already perform other attacks unless strict KEX is negotiated.
Suggested Fix
Add zero-point checks in hybrid_mlkem.rs matching the ones in curve25519.rs:
// In server_dh, after line 93:
let mut c_pk1 = MontgomeryPoint([0; 32]);
c_pk1.0.copy_from_slice(c_pk1_bytes);
if c_pk1.0 == [0u8; 32] {
return Err(Error::Kex);
}
// In compute_shared_secret, after line 155:
let mut s_pk1 = MontgomeryPoint([0; 32]);
s_pk1.0.copy_from_slice(s_pk1_bytes);
if s_pk1.0 == [0u8; 32] {
return Err(Error::Kex);
}
Ideally, also validate against the other small-subgroup points on Curve25519 (there are a small number of low-order points that also yield a zero shared secret), matching the comprehensive validation OpenSSH performs.
AI tooling
AI assistancewas used for the code audit and for drafting this report. The finding was manually verified against the project's source at the location cited above before reporting it, and the severity and impact assessment are my own.
{
"affected": [
{
"package": {
"ecosystem": "crates.io",
"name": "russh"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "0.63.0"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-102824"
],
"database_specific": {
"cwe_ids": [
"CWE-327"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-30T23:26:48Z",
"nvd_published_at": "2026-09-29T19:17:24Z",
"severity": "MODERATE"
},
"details": "## Vulnerability\n\nThe hybrid ML-KEM 768 + X25519 key exchange implementation in `russh/src/kex/hybrid_mlkem.rs` does not validate that the remote peer\u0027s X25519 public key is not the zero point (all-zero 32-byte value). This allows a remote peer to force the X25519 contribution to the combined shared secret to zero, reducing the hybrid KEX to a single-algorithm exchange.\n\nAffected code at HEAD (v0.62.4, commit 0089c89):\n\n**Server-side** (`server_dh`, lines 92-93):\n```rust\nlet mut c_pk1 = MontgomeryPoint([0; 32]);\nc_pk1.0.copy_from_slice(c_pk1_bytes);\n// No zero-point check - proceeds to: let k_cl = s_secret * c_pk1;\n```\n\n**Client-side** (`compute_shared_secret`, lines 154-155):\n```rust\nlet mut s_pk1 = MontgomeryPoint([0; 32]);\ns_pk1.0.copy_from_slice(s_pk1_bytes);\n// No zero-point check - proceeds to: let k_cl = x25519_secret * s_pk1;\n```\n\n## Root Cause\n\nCommit a7fc1eb (2026-07-22, \"fix mpint encoding and validate curve25519 keys\") added zero-point validation to the standalone Curve25519 KEX in `russh/src/kex/curve25519.rs` at two locations:\n- `server_dh` line 77: `if client_pubkey.0 == [0u8; 32] { return Err(crate::Error::Kex); }`\n- `compute_shared_secret` line 122: `if remote_pubkey.0 == [0u8; 32] { return Err(crate::Error::Kex); }`\n\nThe same X25519 scalar multiplication pattern appears in `hybrid_mlkem.rs`, but the fix was not applied there.\n\n## Proof of Concept\n\nA malicious SSH client negotiating `mlkem768x25519-sha256` can send a KEX_HYBRID_INIT message containing a valid ML-KEM 768 encapsulation key followed by 32 zero bytes as the X25519 component.\n\nWhen the server computes `k_cl = s_secret * c_pk1`, the result is the zero point regardless of the server\u0027s secret scalar. The combined shared secret `K = SHA-256(k_pq || k_cl)` then depends only on the ML-KEM component. The same attack works in reverse against a client connecting to a malicious server.\n\nThe zero X25519 public key passes all existing validation (the length check on line 78 succeeds since 32 bytes is correct). No panic or crash occurs - the exchange completes successfully with a weakened shared secret.\n\n## Impact\n\nThe purpose of hybrid key exchange is defense-in-depth: if either the classical algorithm (X25519) or the post-quantum algorithm (ML-KEM 768) is broken, the combined secret remains secure. By injecting a zero X25519 public key, an attacker eliminates the classical contribution entirely, reducing security to depend solely on ML-KEM.\n\nThis matters in two scenarios:\n1. If ML-KEM 768 is later found to have a weakness (the explicit threat model hybrid KEX is designed to mitigate), sessions where the X25519 component was zeroed out lose their fallback protection.\n2. An active network attacker who can intercept KEX could downgrade the hybrid exchange to effectively single-algorithm security without either peer detecting it.\n\nThe severity is MEDIUM rather than HIGH because the ML-KEM component still provides strong security today, and an active attacker who can modify KEX messages can already perform other attacks unless strict KEX is negotiated.\n\n## Suggested Fix\n\nAdd zero-point checks in `hybrid_mlkem.rs` matching the ones in `curve25519.rs`:\n\n```rust\n// In server_dh, after line 93:\nlet mut c_pk1 = MontgomeryPoint([0; 32]);\nc_pk1.0.copy_from_slice(c_pk1_bytes);\nif c_pk1.0 == [0u8; 32] {\n return Err(Error::Kex);\n}\n\n// In compute_shared_secret, after line 155:\nlet mut s_pk1 = MontgomeryPoint([0; 32]);\ns_pk1.0.copy_from_slice(s_pk1_bytes);\nif s_pk1.0 == [0u8; 32] {\n return Err(Error::Kex);\n}\n```\n\nIdeally, also validate against the other small-subgroup points on Curve25519 (there are a small number of low-order points that also yield a zero shared secret), matching the comprehensive validation OpenSSH performs.\n\n### AI tooling\n\nAI assistancewas used for the code audit and for drafting this report. The finding was manually verified against the project\u0027s source at the location cited above before reporting it, and the severity and impact assessment are my own.",
"id": "GHSA-w3jg-pjxf-73p4",
"modified": "2026-09-30T23:26:48Z",
"published": "2026-09-30T23:26:48Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/Eugeny/russh/security/advisories/GHSA-w3jg-pjxf-73p4"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102824"
},
{
"type": "WEB",
"url": "https://github.com/Eugeny/russh/commit/8da8967f196472576b1565d518a0ed60fce60f0c"
},
{
"type": "PACKAGE",
"url": "https://github.com/Eugeny/russh"
},
{
"type": "WEB",
"url": "https://github.com/Eugeny/russh/releases/tag/v0.63.0"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
"type": "CVSS_V3"
}
],
"summary": "Russh: Missing X25519 zero-point validation in hybrid ML-KEM key exchange"
}
Mitigation MIT-24
Strategy: Libraries or Frameworks
- When there is a need to store or transmit sensitive data, use strong, up-to-date cryptographic algorithms to encrypt that data. Select a well-vetted algorithm that is currently considered to be strong by experts in the field, and use well-tested implementations. As with all cryptographic mechanisms, the source code should be available for analysis.
- For example, US government systems require FIPS 140-2 certification [REF-1192].
- Do not develop custom or private cryptographic algorithms. They will likely be exposed to attacks that are well-understood by cryptographers. Reverse engineering techniques are mature. If the algorithm can be compromised if attackers find out how it works, then it is especially weak.
- Periodically ensure that the cryptography has not become obsolete. Some older algorithms, once thought to require a billion years of computing time, can now be broken in days or hours. This includes MD4, MD5, SHA1, DES, and other algorithms that were once regarded as strong. [REF-267]
Mitigation MIT-52
Ensure that the design allows one cryptographic algorithm to be replaced with another in the next generation or version. Where possible, use wrappers to make the interfaces uniform. This will make it easier to upgrade to stronger algorithms. With hardware, design the product at the Intellectual Property (IP) level so that one cryptographic algorithm can be replaced with another in the next generation of the hardware product.
Mitigation
Carefully manage and protect cryptographic keys (see CWE-320). If the keys can be guessed or stolen, then the strength of the cryptography itself is irrelevant.
Mitigation MIT-4
Strategy: Libraries or Frameworks
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
- Industry-standard implementations will save development time and may be more likely to avoid errors that can occur during implementation of cryptographic algorithms. Consider the ESAPI Encryption feature.
Mitigation MIT-25
When using industry-approved techniques, use them correctly. Don't cut corners by skipping resource-intensive steps (CWE-325). These steps are often essential for preventing common attacks.
CAPEC-20: Encryption Brute Forcing
An attacker, armed with the cipher text and the encryption algorithm used, performs an exhaustive (brute force) search on the key space to determine the key that decrypts the cipher text to obtain the plaintext.
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-473: Signature Spoof
An attacker generates a message or datablock that causes the recipient to believe that the message or datablock was generated and cryptographically signed by an authoritative or reputable source, misleading a victim or victim operating system into performing malicious actions.
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.
CAPEC-608: Cryptanalysis of Cellular Encryption
The use of cryptanalytic techniques to derive cryptographic keys or otherwise effectively defeat cellular encryption to reveal traffic content. Some cellular encryption algorithms such as A5/1 and A5/2 (specified for GSM use) are known to be vulnerable to such attacks and commercial tools are available to execute these attacks and decrypt mobile phone conversations in real-time. Newer encryption algorithms in use by UMTS and LTE are stronger and currently believed to be less vulnerable to these types of attacks. Note, however, that an attacker with a Cellular Rogue Base Station can force the use of weak cellular encryption even by newer mobile devices.
CAPEC-614: Rooting SIM Cards
SIM cards are the de facto trust anchor of mobile devices worldwide. The cards protect the mobile identity of subscribers, associate devices with phone numbers, and increasingly store payment credentials, for example in NFC-enabled phones with mobile wallets. This attack leverages over-the-air (OTA) updates deployed via cryptographically-secured SMS messages to deliver executable code to the SIM. By cracking the DES key, an attacker can send properly signed binary SMS messages to a device, which are treated as Java applets and are executed on the SIM. These applets are allowed to send SMS, change voicemail numbers, and query the phone location, among many other predefined functions. These capabilities alone provide plenty of potential for abuse.
CAPEC-97: Cryptanalysis
Cryptanalysis is a process of finding weaknesses in cryptographic algorithms and using these weaknesses to decipher the ciphertext without knowing the secret key (instance deduction). Sometimes the weakness is not in the cryptographic algorithm itself, but rather in how it is applied that makes cryptanalysis successful. An attacker may have other goals as well, such as: Total Break (finding the secret key), Global Deduction (finding a functionally equivalent algorithm for encryption and decryption that does not require knowledge of the secret key), Information Deduction (gaining some information about plaintexts or ciphertexts that was not previously known) and Distinguishing Algorithm (the attacker has the ability to distinguish the output of the encryption (ciphertext) from a random permutation of bits).