Use After Free in Linux
CVE-2025-21786
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.
Vulnerability class: Use-After-Free
EPSS: 0.002 (13.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.8 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Affected products
- Linux — versions 68f83057b913467a999e1bf9e0da6a119668f769, 6.11, 0
- Linux Linux_kernel
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2025-21786?
- CVE-2025-21786 is a high-severity vulnerability in Linux, classified under Use After Free. CVSS score: 7.8/10. Published 2025-02-27.
- How severe is CVE-2025-21786?
- High severity. CVSS v3 base score is 7.8 out of 10.