{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.6.8"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "86d00910b2b2d2d07503fee9b572906daefab7f1"
            },
            {
              "fixed": "ea1d9e301cc3f6d20d141058e4a0c4befc599b62"
            }
          ],
          "repo": "https://github.com/authlib/joserfc",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-gg9x-qcx2-xmrh"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-1391",
      "CWE-287",
      "CWE-326"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49852.json"
  },
  "details": "joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.6.8, joserfc.jwt.decode accepts attacker-forged HMAC-signed tokens when the caller-supplied verification key is the empty string or None, because HMACAlgorithm.sign and HMACAlgorithm.verify in src/joserfc/_rfc7518/jws_algs.py pass the output of OctKey.get_op_key(...) to hmac.new(...) and OctKey.import_key in src/joserfc/_rfc7518/oct_key.py only emits a SecurityWarning for keys shorter than 14 bytes without rejecting zero-length input. This issue is fixed in version 1.6.8.",
  "id": "CVE-2026-49852",
  "modified": "2026-07-25T03:56:24.712411809Z",
  "published": "2026-07-17T19:14:58.019Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/authlib/joserfc/releases/tag/1.6.8"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49852.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/authlib/joserfc/security/advisories/GHSA-gg9x-qcx2-xmrh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-49852"
    },
    {
      "type": "FIX",
      "url": "https://github.com/authlib/joserfc/commit/86d00910b2b2d2d07503fee9b572906daefab7f1"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "joserfc: HS256/HS384/HS512 verify accepts empty/nil HMAC key (cross-language sibling of CVE-2026-45363)"
}