{"id":"DEBIAN-CVE-2026-87853","details":"A flaw was found in SSSD's IdP authentication provider. The eval_access_token_buf() function compares the OIDC subject identifier using strncmp() with the authenticated user's identifier length, performing a prefix comparison instead of an exact match. An attacker whose IdP identifier is a strict prefix of a target user's identifier can authenticate as the target user.","modified":"2026-10-01T03:03:52.170642830Z","published":"2026-09-09T17:17:52.827Z","upstream":["CVE-2026-87853"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-87853"}],"affected":[{"package":{"name":"sssd","ecosystem":"Debian:12","purl":"pkg:deb/debian/sssd?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.10.1-1","2.10.1-2","2.11.1-1","2.11.1-2","2.11.1-2.1","2.12.0-1","2.12.0-2","2.12.0-3~exp0","2.12.0-4","2.13.1-1","2.13.1-2","2.13.1-3","2.8.2-4","2.8.2-4+deb12u1","2.9.1-1","2.9.1-2","2.9.2-1","2.9.4-1","2.9.4-1.1","2.9.4-1.1~exp1","2.9.4-2","2.9.5-1","2.9.5-2","2.9.5-3","2.9.5-4","2.9.5-5"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-87853.json"}},{"package":{"name":"sssd","ecosystem":"Debian:13","purl":"pkg:deb/debian/sssd?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.10.1-2","2.11.1-1","2.11.1-2","2.11.1-2.1","2.12.0-1","2.12.0-2","2.12.0-3~exp0","2.12.0-4","2.13.1-1","2.13.1-2","2.13.1-3"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-87853.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}