What’s Vulnerable › Vulnerabilities

CVE-2021-47110: x86/kvm: Disable kvmclock on all CPUs on shutdown

• Severity: high (CVSS 7.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-03-15 · updated 2026-06-17
• Weakness: CWE-459

Description

In the Linux kernel, the following vulnerability has been resolved: x86/kvm: Disable kvmclock on all CPUs on shutdown Currenly, we disable kvmclock from machine_shutdown() hook and this only happens for boot CPU. We need to disable it for all CPUs to guard against memory corruption e.g. on restore from hibernate. Note, writing '0' to kvmclock MSR doesn't clear memory location, it just prevents hypervisor from updating the location so for the short while after write and while CPU is still alive, the clock remains usable and correct so we don't need to switch to some other clocksource.

Affected products

• Linux kernel: before 5.4.125; from 5.5 before 5.10.43; from 5.11 before 5.12.10; 5.13-rc1 — fixed in 5.10.43, 5.12.10, 5.4.125

How to fix

Upgrade to a fixed version: Linux kernel 5.10.43, 5.12.10, 5.4.125. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/1df2dc09926f61319116c80ee85701df33577d70
• https://git.kernel.org/stable/c/3b0becf8b1ecf642a9edaf4c9628ffc641e490d6
• https://git.kernel.org/stable/c/9084fe1b3572664ad276f427dce575f580c9799a
• https://git.kernel.org/stable/c/c02027b5742b5aa804ef08a4a9db433295533046
• https://git.kernel.org/stable/c/1df2dc09926f61319116c80ee85701df33577d70
• https://git.kernel.org/stable/c/3b0becf8b1ecf642a9edaf4c9628ffc641e490d6
• https://git.kernel.org/stable/c/9084fe1b3572664ad276f427dce575f580c9799a
• https://git.kernel.org/stable/c/c02027b5742b5aa804ef08a4a9db433295533046

Get alerted when CVE-2021-47110 or the next vulnerability affects your stack