Executive brief
SSSD is a system daemon that manages user and group information on Unix-like systems. A flaw in the NSS responder component causes it to leak uninitialized heap memory to local clients querying group membership information, potentially exposing cached directory data and memory layout details that could assist attackers in bypassing security protections.
Technical details
The sss_nss_protocol_fill_initgr() function in SSSD's NSS responder pre-allocates buffer space for all group entries in an initgroups reply but fails to shrink the packet when groups are skipped due to access control policies, leaving uninitialized heap bytes in the transmitted response. This is a use-of-uninitialized-resource vulnerability (CWE-908) triggered by local attackers who can connect to the SSSD NSS responder Unix socket. The disclosed data is limited to directory-level information and heap pointers from the sssd_nss process; sensitive credentials and authentication tokens in separate processes are not exposed. While the primary concern is heap pointer disclosure that could facilitate ASLR bypass when chained with a separate memory-corruption flaw, mitigations are currently unavailable.
Affected products
- SSSD SSSD
Timeline
- 2026-08-04: disclosed