CVE-2026-87853

Published: Sep 9, 2026Modified: Oct 21, 2026

7.5

Vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitability: 1.6 / Impact: 5.9

Source: secalert@redhat.com (Secondary)

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.

Related CWEs

CWE-187

Partial String Comparison

The product performs a comparison that only examines a portion of a factor before determining whether there is a match, such as a substring, leading to resultant weaknesses.

References (3)

https://access.redhat.com/errata/RHSA-2026:77534

Source: secalert@redhat.com

https://access.redhat.com/security/cve/CVE-2026-87853

Source: secalert@redhat.com

https://bugzilla.redhat.com/show_bug.cgi?id=2530888

Source: secalert@redhat.com

Timeline

No history available yet.