In the Linux kernel, the following vulnerability has been resolved: workqueue: Fix NULL current_pwq deref in chained work check current_wq_worker()… (CVE-2026-99058)

The Linux kernel workqueue vulnerability (CVE-2026-99058) involves a NULL pointer dereference in the chained work check. The function current_wq_worker() only confirms that the current task is a kworker but does not ensure that the worker is executing a work item, as worker->current_pwq is only set during work execution. If is_chained_work() is called while queueing on a draining or destroying workqueue, a kworker not executing work may cause a NULL dereference due to worker->current_pwq being NULL. The fix adds a guard to check worker->current_pwq before performing the chained-work test, preventing the fault and allowing proper warning emission.

This vulnerability could cause a kernel fault (NULL pointer dereference) under specific conditions involving workqueue draining or destruction, potentially leading to system instability or crashes. There is no indication of remote exploitability or privilege escalation from the provided data.

A fix has been applied to the Linux kernel to guard against NULL dereference in the chained work check. Users should update to a kernel version including this fix once available. No additional mitigation steps are indicated.