What’s Vulnerable › Vulnerabilities

CVE-2025-39976: futex: Use correct exit on failure from futex_hash_allocate_default()

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-10-15 · updated 2026-10-19

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().

Affected products

• Linux kernel: 6.16 — fixed in 6.17

How to fix

Upgrade to a fixed version: Linux kernel 6.17. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/4ec3c15462b9f44562f45723a92e2807746ba7d1
• https://git.kernel.org/stable/c/f1635765cd0fdbf27b04d9a50be91a01b5adda13

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