CVE-2026-63938 KVM: SEV: Check PSC request indices against the actual size of the buffer

What is CVE-2026-63938?

CVE-2026-63938 is a critical memory corruption vulnerability in Linux kernel, published on 19 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:

KVM: SEV: Check PSC request indices against the actual size of the buffer

When processing Page State Change (PSC) requests, validate the PSC buffer against the effective size of the scratch area, which could be less than the maximum size if the guest provided a pointer that isn't exactly at the start of the GHCB shared buffer.

Weakness: CWE-125

Which versions are affected by CVE-2026-63938?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2026-63938?

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-2026-63938 being exploited?

There is no known exploitation of CVE-2026-63938 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2026-63938, DEBIAN-CVE-2026-63938, GHSA-q47x-vhx7-rrvj, UBUNTU-CVE-2026-63938.