cjose — security advisory

{
  "id": "6597eb3856219fdde934df208b6855aa34c475ef49b74ac79a326e974028c8da",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-53939",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-53939",
    "summary": "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).",
    "evidence": "osv:UBUNTU-CVE-2026-53939",
    "products": [
      {
        "name": {
          "value": "cjose",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.4.1-3ubuntu1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.5.1+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.5.1+dfsg1-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.5.1+dfsg1-2build1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.6.0+dfsg1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "0.6.0+dfsg1-1ubuntu0.1~esm1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "cjose",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.6.1+dfsg1-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "0.6.1+dfsg1-1ubuntu0.1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "cjose",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.6.1+dfsg1-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "0.6.1+dfsg1-3",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "0.6.1+dfsg1-3ubuntu1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "0.6.1+dfsg1-3ubuntu1.1",
            "evidence": "/affected/2/versions"
          }
        ]
      },
      {
        "name": {
          "value": "cjose",
          "evidence": "/affected/3/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.6.2.2-1",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "0.6.2.2-1build1",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "0.6.2.2-1build2",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "0.6.2.2-1build3",
            "evidence": "/affected/3/versions"
          }
        ]
      },
      {
        "name": {
          "value": "cjose",
          "evidence": "/affected/4/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.6.2.4-1",
            "evidence": "/affected/4/versions"
          },
          {
            "value": "0.6.2.8-1",
            "evidence": "/affected/4/versions"
          }
        ]
      },
      {
        "name": {
          "value": "cjose",
          "evidence": "/affected/5/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "0.6.2.3-1",
            "evidence": "/affected/5/versions"
          },
          {
            "value": "0.6.2.4-1",
            "evidence": "/affected/5/versions"
          }
        ]
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "UBUNTU-CVE-2026-53939",
      "aliases": [
        "UBUNTU-CVE-2026-53939"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "cjose",
            "purl": "pkg:deb/ubuntu/cjose?arch=source&distro=esm-apps%2Fbionic",
            "ecosystem": "Ubuntu:Pro:18.04:LTS"
          },
          "versions": [
            "0.4.1-3ubuntu1",
            "0.5.1+dfsg1-1",
            "0.5.1+dfsg1-2",
            "0.5.1+dfsg1-2build1",
            "0.6.0+dfsg1-1",
            "0.6.0+dfsg1-1ubuntu0.1~esm1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53939.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "libcjose0",
                "binary_version": "0.6.0+dfsg1-1ubuntu0.1~esm1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "cjose",
            "purl": "pkg:deb/ubuntu/cjose?arch=source&distro=focal",
            "ecosystem": "Ubuntu:20.04:LTS"
          },
          "versions": [
            "0.6.1+dfsg1-1",
            "0.6.1+dfsg1-1ubuntu0.1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53939.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "libcjose0",
                "binary_version": "0.6.1+dfsg1-1ubuntu0.1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "cjose",
            "purl": "pkg:deb/ubuntu/cjose?arch=source&distro=jammy",
            "ecosystem": "Ubuntu:22.04:LTS"
          },
          "versions": [
            "0.6.1+dfsg1-1",
            "0.6.1+dfsg1-3",
            "0.6.1+dfsg1-3ubuntu1",
            "0.6.1+dfsg1-3ubuntu1.1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53939.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "libcjose0",
                "binary_version": "0.6.1+dfsg1-3ubuntu1.1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "cjose",
            "purl": "pkg:deb/ubuntu/cjose?arch=source&distro=noble",
            "ecosystem": "Ubuntu:24.04:LTS"
          },
          "versions": [
            "0.6.2.2-1",
            "0.6.2.2-1build1",
            "0.6.2.2-1build2",
            "0.6.2.2-1build3"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53939.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "libcjose0",
                "binary_version": "0.6.2.2-1build3"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "cjose",
            "purl": "pkg:deb/ubuntu/cjose?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "0.6.2.4-1",
            "0.6.2.8-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53939.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "libcjose0",
                "binary_version": "0.6.2.8-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "cjose",
            "purl": "pkg:deb/ubuntu/cjose?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "0.6.2.3-1",
            "0.6.2.4-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-53939.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "libcjose0",
                "binary_version": "0.6.2.4-1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T12:59:03.521533011Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-53939"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-53939",
        "https://www.cve.org/CVERecord?id=CVE-2026-53939"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-53939",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 359248,
  "published_at": "2026-09-09T00:17:00+00:00"
}