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.
History

Thu, 08 Oct 2026 23:45:00 +0000

Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:10 cpe:/o:redhat:enterprise_linux:10.2
References

Thu, 10 Sep 2026 21:30:00 +0000

Type Values Removed Values Added
First Time appeared Redhat openshift Container Platform
Sssd
Sssd sssd
Vendors & Products Redhat openshift Container Platform
Sssd
Sssd sssd

Thu, 10 Sep 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Thu, 10 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

threat_severity

Moderate


Wed, 09 Sep 2026 16:30:00 +0000

Type Values Removed Values Added
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.
Title Sssd: sssd: idp authentication prefix comparison allows cross-user impersonation
First Time appeared Redhat
Redhat enterprise Linux
Redhat openshift
Weaknesses CWE-187
CPEs cpe:/a:redhat:openshift:4
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat openshift
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published: 2026-09-09T16:06:25.638Z

Updated: 2026-10-21T18:51:48.396Z

Reserved: 2026-09-09T13:00:35.698Z

Link: CVE-2026-87853

cve-icon Vulnrichment

Updated: 2026-09-09T18:28:47.683Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-09-09T17:17:52.827

Modified: 2026-10-21T19:17:04.200

Link: CVE-2026-87853

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-09-09T14:15:45Z

Links: CVE-2026-87853 - Bugzilla