CVE-2026-68161 in Linux
Summary
by MITRE • 08/10/2026
In the Linux kernel, the following vulnerability has been resolved:
sctp: close UDP tunnel sockets during netns teardown
proc_sctp_do_udp_port() starts per-net SCTP UDP tunneling sockets when net.sctp.udp_port is set, and stops/restarts them when the sysctl value changes. The netns exit path does not stop these sockets, so a namespace can be torn down while its SCTP UDP tunnel sockets are still installed.
Close the UDP tunnel sockets from sctp_ctrlsock_exit() after unregistering the per-net sysctl table. This prevents new sysctl writes from racing in while the sockets are being released, and closes the sockets before the control socket is destroyed.
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Analysis
by VulDB Data Team • 08/10/2026
The vulnerability described represents a critical resource management issue within the Linux kernel's SCTP (Stream Control Transmission Protocol) implementation that could lead to system instability and potential security implications during network namespace teardown operations. This flaw specifically affects the handling of UDP tunnel sockets used by SCTP for encapsulation purposes, creating a race condition scenario where network resources remain allocated even after their containing namespace has been destroyed.
The technical root cause lies in the improper synchronization between the network namespace cleanup process and the destruction of SCTP UDP tunnel sockets. When a network namespace is being torn down, the kernel's netns exit path fails to properly terminate the per-net SCTP UDP tunnel sockets that were created during the initialization phase. These sockets remain active and registered in the system even though their parent namespace has been destroyed, creating a dangling reference situation that can lead to memory leaks and potential resource exhaustion.
The vulnerability manifests through the proc_sctp_do_udp_port() function which manages the lifecycle of SCTP UDP tunneling sockets by starting them when the net.sctp.udp_port sysctl parameter is set and restarting them when configuration changes occur. However, during namespace teardown, this function does not execute its cleanup routine, leaving these sockets in an inconsistent state where they can no longer be properly managed or accessed. This creates a race condition between ongoing system operations and the socket destruction process, potentially allowing for invalid memory access patterns or unexpected behavior.
The operational impact of this vulnerability extends beyond simple resource leakage, as it can affect the stability of systems running multiple network namespaces with SCTP services. When namespace teardown occurs while sockets remain active, it can lead to kernel panics, memory corruption, or denial of service conditions that compromise system integrity. The race condition between new sysctl writes and socket destruction creates additional complexity in system behavior, making the vulnerability particularly challenging to detect and mitigate in production environments.
The fix implemented addresses this issue by modifying the sctp_ctrlsock_exit() function to properly close UDP tunnel sockets before unregistering the per-net sysctl table. This ensures that socket cleanup occurs in the correct order, preventing new sysctl writes from interfering with the destruction process and guaranteeing that sockets are closed before their controlling structures are destroyed. The solution follows proper resource management principles and eliminates the race condition that previously allowed for inconsistent socket states during namespace teardown operations.
From a security perspective, this vulnerability aligns with CWE-129 and CWE-362 categories related to improper handling of resources and race conditions in kernel space operations. The issue also intersects with ATT&CK techniques involving system compromise through resource exhaustion and kernel manipulation. The fix demonstrates proper kernel development practices by ensuring deterministic cleanup order and preventing dangling references that could be exploited for privilege escalation or denial of service attacks.
This vulnerability highlights the complexity of managing network resources in kernel space where multiple subsystems must coordinate properly during initialization and teardown phases. The solution represents a defensive programming approach that ensures all allocated resources are properly accounted for and released, maintaining system stability even under adverse conditions such as unexpected namespace destruction sequences. The implementation follows established kernel patterns for resource management and demonstrates the importance of proper synchronization in concurrent systems where multiple threads or processes may interact with the same resources during cleanup operations.