CVE-2026-64558 s390/pkey: Check length in pkey_pckmo handler implementation
A missing length check in the s390 pkey handler allows buffer overflows, potentially enabling code execution or privilege escalation in the Linux kernel.
- 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-2026-64558?
CVE-2026-64558 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_pckmo handler implementation
Explicitly check the length of the target buffer in the pkey_pckmo implementation of the key_to_protkey() handler function. The handler function fails, if the generated output data exceeds the length of the provided target buffer.
Weakness: CWE-122
Which versions are affected by CVE-2026-64558?
How do I fix CVE-2026-64558?
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-2026-64558 being exploited?
There is no known exploitation of CVE-2026-64558 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-64558, DEBIAN-CVE-2026-64558, GHSA-82p5-pf6r-jcxr, UBUNTU-CVE-2026-64558.