CVE-2026-87853

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.

• CWE-187

• https://access.redhat.com/security/cve/CVE-2026-87853
• https://bugzilla.redhat.com/show_bug.cgi?id=2530888

Published

Sep 9, 2026

Last Modified

Sep 10, 2026

Status

Awaiting Analysis

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