{"id":"UBUNTU-CVE-2026-102266","details":"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.","modified":"2026-09-29T23:41:45.181045963Z","published":"2026-09-29T00:00:00Z","upstream":["CVE-2026-102266"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-102266"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-102266"},{"type":"REPORT","url":"https://github.com/jpadilla/pyjwt/security/advisories/GHSA-9j54-fg26-wv3r"},{"type":"REPORT","url":"https://github.com/jpadilla/pyjwt/commit/f91ed44dd65baaf457f4b3353ed35e98a753934c"},{"type":"REPORT","url":"https://github.com/jpadilla/pyjwt/releases/tag/2.14.0"}],"affected":[{"package":{"name":"pyjwt","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/pyjwt?arch=source&distro=esm-infra-legacy%2Fxenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.0.0-0ubuntu1","1.3.0-1","1.3.0-1ubuntu0.1","1.3.0-1ubuntu0.1+esm1","1.3.0-1ubuntu0.1+esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"python-jwt","binary_version":"1.3.0-1ubuntu0.1+esm2"},{"binary_name":"python3-jwt","binary_version":"1.3.0-1ubuntu0.1+esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-102266.json"}},{"package":{"name":"pyjwt","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/pyjwt?arch=source&distro=esm-infra%2Fbionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.4.2-1.1","1.5.3+ds1-1","1.5.3+ds1-1ubuntu0.1","1.5.3+ds1-1ubuntu0.1+esm1","1.5.3+ds1-1ubuntu0.1+esm2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.5.3+ds1-1ubuntu0.1+esm2","binary_name":"python-jwt"},{"binary_name":"python3-jwt","binary_version":"1.5.3+ds1-1ubuntu0.1+esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-102266.json"}},{"package":{"name":"pyjwt","ecosystem":"Ubuntu:Pro:20.04:LTS","purl":"pkg:deb/ubuntu/pyjwt?arch=source&distro=esm-infra%2Ffocal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.7.0-2","1.7.1-1","1.7.1-2ubuntu1","1.7.1-2ubuntu2","1.7.1-2ubuntu2.1","1.7.1-2ubuntu2.1+esm1","1.7.1-2ubuntu2.1+esm2"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-jwt","binary_version":"1.7.1-2ubuntu2.1+esm2"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-102266.json"}},{"package":{"name":"pyjwt","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/pyjwt?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.7.1-2ubuntu2","2.1.0-1","2.3.0-1","2.3.0-1ubuntu0.1","2.3.0-1ubuntu0.2","2.3.0-1ubuntu0.3","2.3.0-1ubuntu0.4"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-jwt","binary_version":"2.3.0-1ubuntu0.4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-102266.json"}},{"package":{"name":"pyjwt","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/pyjwt?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.7.0-1","2.7.0-1ubuntu0.1","2.7.0-1ubuntu0.2"],"ecosystem_specific":{"binaries":[{"binary_version":"2.7.0-1ubuntu0.2","binary_name":"python3-jwt"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-102266.json"}},{"package":{"name":"pyjwt","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/pyjwt?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"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"],"ecosystem_specific":{"binaries":[{"binary_version":"2.10.1-4ubuntu1.1","binary_name":"python3-jwt"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-102266.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"},{"type":"Ubuntu","score":"medium"}]}