High severity7.5NVD Advisory· Published Sep 9, 2026· Updated Oct 21, 2026
CVE-2026-87853
CVE-2026-87853
Description
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.
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Affected products
31- osv-coords30 versionspkg:rpm/almalinux/libsss_idmappkg:rpm/almalinux/python3-sss-murmurpkg:rpm/almalinux/sssdpkg:rpm/almalinux/sssd-adpkg:rpm/almalinux/sssd-clientpkg:rpm/almalinux/sssd-commonpkg:rpm/almalinux/libsss_sudopkg:rpm/almalinux/sssd-winbind-idmappkg:rpm/almalinux/python3-sssdconfigpkg:rpm/almalinux/sssd-toolspkg:rpm/opensuse/sssd&distro=openSUSE%20Tumbleweedpkg:rpm/almalinux/python3-ssspkg:rpm/almalinux/sssd-nfs-idmappkg:rpm/almalinux/libipa_hbacpkg:rpm/almalinux/libsss_autofspkg:rpm/almalinux/libsss_certmappkg:rpm/almalinux/python3-libipa_hbacpkg:rpm/almalinux/sssd-common-pacpkg:rpm/almalinux/sssd-dbuspkg:rpm/almalinux/libsss_nss_idmappkg:rpm/almalinux/libsss_nss_idmap-develpkg:rpm/almalinux/python3-libsss_nss_idmappkg:rpm/almalinux/sssd-idppkg:rpm/almalinux/sssd-ipapkg:rpm/almalinux/sssd-kcmpkg:rpm/almalinux/sssd-krb5pkg:rpm/almalinux/sssd-krb5-commonpkg:rpm/almalinux/sssd-ldappkg:rpm/almalinux/sssd-passkeypkg:rpm/almalinux/sssd-proxy
< 2.12.0-3.el10_2.2+ 29 more
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.13.1-3.1
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
- (no CPE)range: < 2.12.0-3.el10_2.2
Patches
Vulnerability mechanics
References
3News mentions
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