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.

CVSS 3.1

7.5CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS

0.3% chance of exploitation in the next 30 days; higher than 25% of CVEs (scores of 2026-10-25)

CWE

CWE-187

Published

2026-09-09

Modified

2026-10-21

Record from

the NVD, synced 2026-10-22

References

• https://access.redhat.com/errata/RHSA-2026:77534
• https://access.redhat.com/security/cve/CVE-2026-87853
• https://bugzilla.redhat.com/show_bug.cgi?id=2530888

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