GHSA-434V-X5QV-PMH6

Vulnerability from github – Published: 2026-03-26 17:58 – Updated: 2026-03-26 17:58
VLAI?
Summary
libcrux has All-Zero Key Generation Upon Catastrophic RNG Failure
Details

The libcrux-ed25519 key generation samples Ed25519 secret keys from a provided CSPRNG in a loop for up to 100 attempts until a non-zero key is found. If a non-zero key could not be sampled within 100 attempts the key generation function would silently continue with an all-zero buffer as the secret key.

Impact

This bug only occurs in the event of a catastrophic failure of the CSPRNG, but would allow anyone to forge signatures under the resulting static signing key.

Mitigation

Instead of silently continuing with an all-zero signing key, starting from version 0.0.7 key generation will error in the case of 100 failed attempts at sampling a valid key.

Severity ?
8.2 (High)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "libcrux-ed25519"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.0.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-1240",
      "CWE-331",
      "CWE-392"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-26T17:58:55Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "The libcrux-ed25519 key generation samples Ed25519 secret keys from a provided CSPRNG in a loop for up to 100 attempts until a non-zero key is found.  If a non-zero key could not be sampled within 100 attempts the key generation function would silently continue with an all-zero buffer as the secret key.\n\n## Impact\nThis bug only occurs in the event of a catastrophic failure of the CSPRNG, but would allow anyone to forge signatures under the resulting static signing key.\n\n## Mitigation\nInstead of silently continuing with an all-zero signing key, starting from version `0.0.7` key generation will error in the case of 100 failed attempts at sampling a valid key.",
  "id": "GHSA-434v-x5qv-pmh6",
  "modified": "2026-03-26T17:58:55Z",
  "published": "2026-03-26T17:58:55Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/cryspen/libcrux/pull/1349"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/cryspen/libcrux"
    },
    {
      "type": "WEB",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0075.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "libcrux has All-Zero Key Generation Upon Catastrophic RNG Failure"
}


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