In the Linux kernel, the following vulnerability has been resolved:

workqueue: Put the pwq after detaching the rescuer from the pool

The commit 68f83057b913("workqueue: Reap workers via kthread_stop() and
remove detach_completion") adds code to reap the normal workers but
mistakenly does not handle the rescuer and also removes the code waiting
for the rescuer in put_unbound_pool(), which caused a use-after-free bug
reported by Cheung Wall.

To avoid the use-after-free bug, the pool’s reference must be held until
the detachment is complete. Therefore, move the code that puts the pwq
after detaching the rescuer from the pool.

References

• https://nvd.nist.gov/vuln/detail/CVE-2025-21786
• https://git.kernel.org/stable/c/835b69c868f53f959d4986bbecd561ba6f38e492
• https://git.kernel.org/stable/c/e76946110137703c16423baf6ee177b751a34b7e
• https://git.kernel.org/stable/c/e7c16028a424dd35be1064a68fa318be4359310f