SB20260727285 - Race condition in Linux kernel x86 kvm

Description

This security bulletin contains information about 1 vulnerability.

1) Race condition (CVE-ID: CVE-2026-64284)

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSSv4: 4.8 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a local user to cause guest memory dirty logging to be incomplete.

The vulnerability exists due to improper synchronization in KVM x86 exit handling when processing fastpath userspace exits. A local user can trigger a fastpath userspace exit to cause guest memory dirty logging to be incomplete.

The issue affects vendor-specific KVM exit handling paths such as VMX, where operations needed before returning control to userspace may be skipped.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/0ffedf43910e44b76c2c1db4e9fbf12b268190c1
• https://git.kernel.org/stable/c/4ad73ef0e7966ecfe67de0060537b4cb14d9acd4
• https://git.kernel.org/stable/c/b3436d9b9b1affe1c3191ac9831308923f5f03c3
• https://git.kernel.org/stable/c/f2ca2b5326211bd38490f0497eb583721ce0bbc0