CVE-2026-93829
Low risk· EPSS 5%Exploitation Probability (EPSS)
Low risk5th percentile - higher than 5% of all known CVEs
Summary
In the Linux kernel SMB client, the cifsd thread can access the tcp_ses structure before the parent thread finishes populating it, causing a race condition. Additionally, the kthread_run macro may start the thread before returning the thread pointer, so if the kernel is preempted the thread sleeps waiting for SIGKILL. The fix moves thread creation after all tcp_ses fields are populated and splits kthread_create from wake_up_process.
Risk Assessment
The race and improper thread initialization can lead to system instability, hangs, or potential memory corruption in kernel context. This affects systems using the SMB/CIFS client.
Recommendation
Update the Linux kernel to a version containing the fix for this CVE. If updating is not possible, consider limiting or monitoring SMB/CIFS client usage.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix races in cifsd thread creation The cifsd demultiplex thread can run and access tcp_ses before the parent thread has finished populating tcp_ses, which the worker thread accesses locklessly. Also, the kthread_run macro may start the thread before returning the thread pointer. Because the pointer is part of the structure that the thread can access, if the kernel is preempted after the thread is spawned, but before the thread pointer is populated and the thread attempts to exit, it will sleep, waiting for a SIGKILL signal. Fix this by moving creation of the thread to after all of tcp_ses'es fields are populated, and spawning the thread last, using a split kthread_create/wake_up_process logic.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS