CVE-2026-116497 in Red Hat
Summary
by MITRE • 10/26/2026
A NULL pointer dereference vulnerability was found in gssproxy. When a GSSX_INIT_SEC_CONTEXT request is received with the target_name field absent, the daemon dereferences the resulting NULL pointer and crashes. The request requires no authentication, allowing any local user to crash the gssproxy daemon via its Unix socket. The daemon does not automatically restart, resulting in a persistent denial of service that also affects dependent services such as Kerberized NFS and IdM.
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Analysis
by VulDB Data Team • 10/26/2026
The vulnerability identified within the gssproxy utility represents a critical failure in input validation logic during the handling of Generic Security Services Application Program Interface (GSS-API) initialization requests. Specifically, when the daemon processes a GSSX_INIT_SEC_CONTEXT message where the target_name field is missing or absent from the packet structure, it fails to perform necessary null checks before attempting to access memory at that location. This oversight leads directly to a NULL pointer dereference, causing the gssproxy process to terminate unexpectedly with an segmentation fault error. The root cause lies in the assumption that all required fields within the security context initialization request are present and valid, which is not guaranteed when interacting over untrusted or poorly constructed inputs.
From an operational perspective, this flaw results in a persistent denial of service condition for any system relying on gssproxy for authentication services. Because the daemon does not automatically restart upon crashing, the impact extends beyond a simple temporary interruption. Services that depend on continuous availability of the GSS-API proxy mechanism are effectively disabled until manual intervention occurs to restore the process. This includes critical infrastructure components such as Kerberized Network File System (NFS) mounts and Identity Management systems used in enterprise environments for centralized authentication and authorization. The loss of gssproxy functionality can lead to widespread connectivity issues, inability to access shared resources, and potential disruption of identity-based access controls across a network segment or entire domain.
The severity of this vulnerability is significantly amplified by its low barrier to exploitation. Since the attack vector requires no prior authentication, any local user on the system can trigger the crash simply by sending a malformed request through the Unix socket interface used for inter-process communication with gssproxy. This characteristic classifies the issue as an unauthenticated remote code execution equivalent in terms of impact, though technically it is limited to denial of service due to the nature of the memory error. The ability for any local user to disrupt system-wide authentication services highlights a significant privilege escalation risk if combined with other vulnerabilities or misconfigurations that allow persistence after restarts.
In terms of industry standard classifications, this vulnerability aligns closely with CWE-476, which denotes NULL Pointer Dereference, indicating improper handling of null pointers leading to application crashes. Furthermore, the exploitation method falls under MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter or Local Application Harvesting depending on subsequent actions, but primarily represents a Denial of Service attack vector often categorized under T1499 in broader contexts of resource exhaustion. The lack of authentication requirement places it within the scope of local privilege escalation pathways where availability is compromised to facilitate further attacks or cause operational disruption.
Mitigation strategies must focus on both immediate remediation and long-term architectural improvements. Administrators should apply vendor-provided patches that update gssproxy to versions containing proper input validation checks for all fields in GSSX_INIT_SEC_CONTEXT requests, ensuring null pointers are detected before dereferencing occurs. In environments where patching is not immediately feasible, restricting access to the Unix socket used by gssproxy can limit exposure. This involves configuring file system permissions so that only trusted services or users with specific privileges can send messages to the daemon, thereby preventing unauthenticated local users from triggering the crash. Additionally, implementing monitoring solutions that detect frequent crashes of the gssproxy process can aid in rapid incident response and minimize downtime by alerting administrators to manual restarts when necessary.