CVE-2026-31554 futex: Require sys_futex_requeue() to have identical flags
A use-after-free vulnerability in the Linux kernel futex requeue operation allows attackers to potentially execute code or escalate privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-31554?
CVE-2026-31554 is a high-severity use after free vulnerability in Linux kernel, published on 24 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
futex: Require sys_futex_requeue() to have identical flags
Nicholas reported that his LLM found it was possible to create a UaF when sys_futex_requeue() is used with different flags. The initial motivation for allowing different flags was the variable sized futex, but since that hasn't been merged (yet), simply mandate the flags are identical, as is the case for the old style sys_futex() requeue operations.
Weakness: CWE-416
Which versions are affected by CVE-2026-31554?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-31554?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-31554 being exploited?
There is no known exploitation of CVE-2026-31554 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-31554, DEBIAN-CVE-2026-31554, GHSA-fqg3-p6v9-g3wx, ROOT-OS-DEBIAN-13-CVE-2026-31554, ROOT-OS-UBUNTU-2404-CVE-2026-31554, UBUNTU-CVE-2026-31554.