CVE-2026-64559 s390/pkey: Check length in PKEY_VERIFYPROTK ioctl
A missing length check in the s390/pkey ioctl allows out-of-bounds reads, potentially causing crashes or code execution.
- 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-2026-64559?
CVE-2026-64559 is a high-severity memory corruption vulnerability in Linux, published on 29 Jul 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:
s390/pkey: Check length in PKEY_VERIFYPROTK ioctl
Explicitly check the buffer length request structure provided by user-space and fail, if it exceeds the buffer size.
Weakness: CWE-125
Which versions are affected by CVE-2026-64559?
How do I fix CVE-2026-64559?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-64559 being exploited?
There is no known exploitation of CVE-2026-64559 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-64559, DEBIAN-CVE-2026-64559, GHSA-qvg4-x45w-c5rj, UBUNTU-CVE-2026-64559.