CVE-2026-104029 in sssd
Summary
by MITRE • 10/06/2026
A flaw was found in SSSD. A local attacker can exploit this vulnerability by sending a specially crafted request to the autofs responder UNIX socket. Due to improper buffer offset calculation during request parsing, the service performs an out-of-bounds memory read. This flaw can cause the autofs responder process to crash, resulting in a denial of service (DoS).
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Analysis
by VulDB Data Team • 10/06/2026
The System Security Services Daemon, commonly known as SSSD, serves as a critical component in Linux and Unix environments for managing identity and authentication services. It acts as an intermediary between local systems and remote directory servers such as Active Directory or LDAP, handling tasks like user lookup, password changes, and automounting via the autofs responder. The vulnerability described herein affects this specific subsystem, highlighting a significant security gap within the daemon's request processing logic. This flaw is particularly concerning because it can be exploited by local attackers who have access to the system but may not possess high-level privileges initially, as exploitation relies on interaction with the autofs responder UNIX socket rather than direct network exposure or remote code execution vectors.
The technical root cause of this vulnerability lies in an improper buffer offset calculation during the parsing of incoming requests sent to the autofs responder. When a client sends a request through the UNIX domain socket interface, SSSD parses the data structure to determine how much memory needs to be read and processed. In this specific scenario, the logic fails to correctly validate or calculate the boundaries of the input buffer relative to the expected message format. This miscalculation leads the service to attempt reading from a memory address that lies outside the allocated bounds for that request context. Such an out-of-bounds memory read is a classic manifestation of CWE-125, which describes situations where software reads past the end of a buffer or array. Unlike write-based vulnerabilities that might allow for arbitrary code execution by overwriting control data, this specific flaw primarily results in reading invalid memory locations, which typically triggers segmentation faults or similar fatal errors within the operating system's memory management unit.
The operational impact of exploiting this vulnerability is predominantly focused on availability rather than confidentiality or integrity. Because the out-of-bounds read causes an immediate crash of the autofs responder process, the primary consequence is a denial of service for automounting services managed by SSSD. For environments relying heavily on network file systems such as NFS or CIFS that are mounted automatically via autofs, this disruption can prevent users from accessing their home directories or other critical shared resources upon login or when attempting to traverse specific directory paths. While the immediate effect is a service crash, repeated exploitation could lead to persistent unavailability of these services until the SSSD daemon is restarted by an administrator with sufficient privileges. This aligns with ATT&CK technique T1499, specifically Endpoint Denial of Service, where adversaries disrupt access to available resources on a system or network.
From a broader security perspective, this vulnerability underscores the risks associated with local privilege escalation paths and the complexity of IPC mechanisms in enterprise identity management systems. Although it does not directly grant code execution rights, crashing critical daemons can be used as part of a larger attack chain to distract administrators, mask other malicious activities, or force system instability that might lead to further exploitation opportunities if recovery procedures are flawed. The vulnerability is categorized under CWE-125 for the out-of-bounds read and relates to CWE-20 for improper input validation, which failed to ensure that the parsed request data remained within safe memory limits before processing.
Mitigation strategies should focus on both immediate remediation and long-term architectural improvements. The most effective solution is to apply the vendor-provided patch or update SSSD to a version where this buffer offset calculation logic has been corrected. Administrators must verify that their systems are running patched versions of the software, as upstream developers typically address such memory safety issues by adding strict bounds checking and validation routines before any memory access occurs. In addition to updating software, organizations should enforce least-privilege principles for local accounts interacting with SSSD services where possible, although mitigating this specific vulnerability primarily requires patching since it relies on the daemon's internal logic rather than external network exposure. Regular auditing of system logs for unexpected crashes in the autofs responder can also help detect potential exploitation attempts early, allowing for rapid incident response before widespread service disruption occurs.