pyjwt — security advisory

{
  "id": "60cbbd11be958557d1b8669eab98f4ede8c0263a1f275e099d774282b7b9bac1",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-102266",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-102266",
    "summary": "PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, HMACAlgorithm.from_jwk is affected because PyJWK verification path used the decoded key without applying prepare_key validation. This occurs when a trusted JWK Set contains an oct entry with an empty k value. As a result, an attacker signs an HMAC token with the same zero-length key accepted by PyJWT. Consequently, forged token can carry arbitrary authenticated claims. This issue is fixed in version 2.14.0.",
    "evidence": "osv:UBUNTU-CVE-2026-102266",
    "products": [
      {
        "name": {
          "value": "pyjwt",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.13.0-1ubuntu1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "2.10.1-4ubuntu1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.12.1-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "2.13.0-1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "pyjwt",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "2.10.1-4ubuntu1.2",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "2.10.1-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.10.1-3",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.10.1-3build1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.10.1-4",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.10.1-4ubuntu1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "2.10.1-4ubuntu1.1",
            "evidence": "/affected/1/versions"
          }
        ]
      }
    ],
    "severity": "critical",
    "structured": {
      "id": "UBUNTU-CVE-2026-102266",
      "aliases": [
        "UBUNTU-CVE-2026-102266"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
        },
        {
          "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"
                },
                {
                  "fixed": "2.13.0-1ubuntu1"
                }
              ]
            }
          ],
          "package": {
            "name": "pyjwt",
            "purl": "pkg:deb/ubuntu/pyjwt?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "2.10.1-4ubuntu1",
            "2.12.1-1",
            "2.13.0-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-102266.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "python3-jwt",
                "binary_version": "2.13.0-1ubuntu1"
              }
            ],
            "availability": "No subscription required"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "2.10.1-4ubuntu1.2"
                }
              ]
            }
          ],
          "package": {
            "name": "pyjwt",
            "purl": "pkg:deb/ubuntu/pyjwt?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "2.10.1-2",
            "2.10.1-3",
            "2.10.1-3build1",
            "2.10.1-4",
            "2.10.1-4ubuntu1",
            "2.10.1-4ubuntu1.1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-102266.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "python3-jwt",
                "binary_version": "2.10.1-4ubuntu1.2"
              }
            ],
            "availability": "No subscription required"
          }
        }
      ],
      "modified": "2026-10-27T11:56:51.343800745Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-102266"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-102266",
        "https://www.cve.org/CVERecord?id=CVE-2026-102266",
        "https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r",
        "https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c",
        "https://github.com/jpadilla/pyjwt/releases/tag/2.14.0",
        "https://ubuntu.com/security/notices/USN-8916-2",
        "https://ubuntu.com/security/notices/USN-8916-1"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-102266",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/1/score"
  },
  "source_id": "core-osv",
  "document_id": 461466,
  "published_at": "2026-09-28T21:17:00+00:00"
}