{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0.6.1"
              },
              {
                "fixed": "0.6.2.6"
              }
            ],
            "source": "AFFECTED_FIELD"
          },
          "events": [
            {
              "introduced": "b122181f5537e928f8e78afd33f96a35bdefa67f"
            },
            {
              "fixed": "7d1aceae7da31fc6975db23f70f3c0485c5d5c43"
            }
          ],
          "repo": "https://github.com/openidc/cjose",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-f6wf-pqg3-6wqq"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-321",
      "CWE-330"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53939.json"
  },
  "details": "OpenIDC/cjose is a C library implementing the Javascript Object Signing and Encryption (JOSE). In versions 0.6.1 through 0.6.2.5, when cjose encrypts a JWE using an AES-CBC-HMAC content-encryption algorithm (`A128CBC-HS256`, `A192CBC-HS384`, or `A256CBC-HS512`) together with any key-management algorithm that generates a fresh content-encryption key (CEK), the CEK is all zero bytes instead of being randomly generated. The resulting JWE is therefore encrypted and authenticated under a fixed, publicly known key, so anyone who obtains the JWE can recover the plaintext and forge or modify the content. This is fixed in version 0.6.2.6 by `_cjose_jwe_set_cek_aes_cbc()` generating the CEK from `RAND_bytes`. A regression test asserts that the `encrypted_key` differs across two encryptions for each AES-CBC-HMAC variant. Until upgrading, for data encrypted with cjose, three options are available. Use an AES-GCM `enc` (`A128GCM` / `A192GCM` / `A256GCM`) instead of an AES-CBC-HMAC `enc`,  use `alg=dir` with a caller-supplied CEK, or avoid using cjose for JWE encryption with the affected algorithm pair. These are mitigations for new ciphertexts only; data already encrypted under the zero key remains compromised and should be re-encrypted (and any secrets it contained rotated).",
  "id": "CVE-2026-53939",
  "modified": "2026-09-12T03:30:43.322835700Z",
  "published": "2026-09-08T23:36:13.668Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/OpenIDC/cjose/releases/tag/v0.6.2.6"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/53xxx/CVE-2026-53939.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/OpenIDC/cjose/security/advisories/GHSA-f6wf-pqg3-6wqq"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-53939"
    },
    {
      "type": "FIX",
      "url": "https://github.com/OpenIDC/cjose/commit/2a6e5bd969fa20059fb00913fb9f57d77ea6a4d9"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "OpenIDC/cjose uses all-zero Content Encryption Key for AES-CBC-HMAC JWE encryption"
}