{"id":"UBUNTU-CVE-2026-75509","details":"joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to version 1.7.3, JWTClaimsRegistry applies membership matching to list-valued iss and sub claims, allowing an array-valued iss that contains the expected issuer to pass an intended equality check and enabling issuer-validation bypass. This issue is fixed in version 1.7.3.","modified":"2026-09-02T19:36:33.976629484Z","published":"2026-08-24T20:17:00Z","upstream":["CVE-2026-75509"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-75509"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-75509"},{"type":"REPORT","url":"https://github.com/authlib/joserfc/security/advisories/GHSA-r74j-q665-7rpj"}],"affected":[{"package":{"name":"joserfc","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/joserfc?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.2-1","1.4.0-1","1.4.1-1","1.4.3-1","1.5.0-1","1.6.2-1"],"ecosystem_specific":{"binaries":[{"binary_name":"python3-joserfc","binary_version":"1.6.2-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-75509.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:L/I:H/A:N"},{"type":"Ubuntu","score":"medium"}]}