Executive brief
SSSD is a system service that handles user authentication on Linux systems. A flaw in its PAM responder allows a local attacker to send a specially crafted request that causes the service to read memory beyond its buffer boundaries, crashing the authentication daemon. This results in denial of service, potentially preventing legitimate users from logging in to systems managed by SSSD.
Technical details
The vulnerability is an out-of-bounds read (CWE-125) in the extract_authtok_v1() function within SSSD's PAM responder. The function fails to validate the auth_token_length field against the remaining buffer size before processing. A local attacker who can connect to the SSSD PAM responder Unix socket can send a crafted protocol v1 request to trigger an out-of-bounds read, causing a process crash and denial of service. The stock PAM client uses protocol v3 and is unaffected; this path is only exploitable via direct socket access with a malicious v1 request.
Affected products
- SSSD Project SSSD
Timeline
- 2026-08-04: disclosed