Hi,

The following vulnerability was published for sssd.

CVE-2026-87853[0]:
| 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.


If you fix the vulnerability please also make sure to include the
CVE (Common Vulnerabilities & Exposures) id in your changelog entry.

For further information see:

[0] https://security-tracker.debian.org/tracker/CVE-2026-87853
https://www.cve.org/CVERecord?id=CVE-2026-87853
[1] https://github.com/SSSD/sssd/pull/9250
[2] https://github.com/SSSD/sssd/commit/f3a324918c1a35bd0195a1de5b17897a0d3b6274 (master)
https://github.com/SSSD/sssd/commit/8180e70a2708dbf8ac6f089119922dec81fcc503 (sssd-2-13)
https://github.com/SSSD/sssd/commit/542411bb0b6e4171d9183fbf364d6cb52d848ad5 (sssd-2-12)

Please adjust the affected versions in the BTS as needed.

Regards,
Salvatore