Race condition in Linux kernel - CVE-2026-64284

Vulnerability identifier: #VU139696

CSH Severity: Low

CVSS v4: 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]

CVE-ID: CVE-2026-64284

CWE-ID: CWE-362

Exploitation vector: Local access

Exploit availability: No public exploit available

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.

Linux kernel
Ubuntu
linux (Ubuntu package)
linux-azure (Ubuntu package)
linux-gcp-7.0 (Ubuntu package)
linux-oracle-7.0 (Ubuntu package)
linux-oem-7.0 (Ubuntu package)
linux-azure-7.0 (Ubuntu package)

Install security update from vendor's repository.

Linux kernel - update to 7.0 rc3
linux (Ubuntu package) - addressed in versions 7.0.0-31.31, 7.0.0-31.31.1, 7.0.0-31.31~24.04.1, 7.0.0-1006.7, 7.0.0-1011.11~24.04.1, 7.0.0-1012.12, 7.0.0-1012.12~24.04.1
linux-azure (Ubuntu package) - addressed in versions 7.0.0-1011.11, 7.0.0-1014.14
linux-gcp-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oracle-7.0 (Ubuntu package) - update to 7.0.0-1011.11~24.04.1
linux-oem-7.0 (Ubuntu package) - update to 7.0.0-1013.13
linux-azure-7.0 (Ubuntu package) - update to 7.0.0-1014.14~24.04.1

• 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

• Race condition in Linux kernel x86 kvm
• Ubuntu update for linux-oem-7.0
• Ubuntu update for linux
• Ubuntu update for linux-gcp-7.0
• Ubuntu update for linux-oracle-7.0
• Ubuntu update for linux-azure
• Ubuntu update for linux-azure-7.0