CVE-2025-39976
Published Oct 15, 2025
Modified Apr 15, 2026
Description
In the Linux kernel, the following vulnerability has been resolved: futex: Use correct exit on failure from futex_hash_allocate_default() copy_process() uses the wrong error exit path from futex_hash_allocate_default(). After exiting from futex_hash_allocate_default(), neither tasklist_lock nor siglock has been acquired. The exit label bad_fork_core_free unlocks both of these locks which is wrong. The next exit label, bad_fork_cancel_cgroup, is the correct exit. sched_cgroup_fork() did not allocate any resources that need to freed. Use bad_fork_cancel_cgroup on error exit from futex_hash_allocate_default().
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References
Frequently Asked Questions
What is CVE-2025-39976? +
In the Linux kernel, the following vulnerability has been resolved:
futex: Use correct exit on failure from futex_hash_allocate_default()
copy_process() uses the wrong error exit path from futex_hash_allocate_default().
After exiting from futex_hash_allocate_default(), neither tasklist_lock
nor siglock has been acquired. The exit label bad_fork_core_free unlocks
both of these locks which is wrong.
The next exit label, bad_fork_cancel_cgroup, is the correct exit.
sched_cgroup_fork() did not allocate any resources that need to freed.
Use bad_fork_cancel_cgroup on error exit from futex_hash_allocate_default().
How do I check if I'm vulnerable to CVE-2025-39976? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.