CVE-2026-104033

A flaw was found in SSSD. When configured to enforce account expiration using LDAP (Lightweight Directory Access Protocol) shadow attributes, SSSD fails to treat an expiration value of zero as an expired account. A user with valid credentials for an expired account can exploit this flaw to bypass access controls and authenticate to the system. This allows unauthorized access to persist after the account was intended to be deactivated.

This vulnerability is rated Moderate because it allows an expired LDAP account to authenticate without authorization, but exploitation requires pre-existing valid credentials and cannot lead to remote code execution or privilege escalation beyond the account's existing privileges. The flaw only affects environments explicitly configured to enforce shadow-based expiration through SSSD using LDAP access control policies. Systems utilizing default SSSD configurations, alternative expiration mechanisms, or centralized directory-level account lockouts are not vulnerable to this bypass.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Until a fix is available, deployments using SSSD's LDAP shadow-based expiration (access_provider = ldap with ldap_access_order including expire and ldap_account_expire_policy = shadow) should not rely on shadowExpire=0 to expire accounts. Set the shadowExpire attribute to a positive past day value so that SSSD correctly treats the account as expired, or enforce account disablement or expiration through directory-side controls that do not depend solely on this client-side SSSD check. If SSSD has cached the affected account's attributes, invalidate the cached entry (for example with sss_cache -u <username>) or restart the sssd service so the updated directory values take effect; note that restarting the service or clearing cached data can briefly interrupt active authentication sessions on the host.