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VulnerabilityPublished Updated

CVE-2024-40953: Linux kernel · KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin()

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 7.9 High · fixed in 5.4.0-1142.152~18.04.1 : patch Linux kernel soon.

Data as of 28 Oct 2026, 11:00 UTC

CVSS 3.1 base score
7.9High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 5.4.0-1142.152~18.04.1, 5.4.0-1145.152~18.04.1, 5.4.0-1143.152~18.04.1 +71
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 12 Jul 2024

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-44.44
Fixed in
  • 6.8.0-44.44
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1015.16
Fixed in
  • 6.8.0-1015.16
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1014.16
Fixed in
  • 6.8.0-1014.16
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1014.16
Fixed in
  • 6.8.0-1014.16
Ubuntu 24.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1010.13
Fixed in
  • 6.8.0-1010.13
Ubuntu 24.04 LTSlinux-ibmpkg:deb/ubuntu/linux-ibm?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1012.12
Fixed in
  • 6.8.0-1012.12

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch addressing this vulnerability is available and should be applied promptly. The fixed kernel versions include multiple updated builds in the 5.4 and 5.15 series as listed in the established facts. Applying these official updates will mitigate the data race issue. No additional mitigation actions are indicated by the vendor advisory.

Description

CVE-2024-40953 is a data race vulnerability in the Linux kernel's KVM subsystem affecting the last_boosted_vcpu variable accessed in the kvm_vcpu_on_spin() function. The issue arises from non-atomic loads and stores to this variable, which can lead to an out-of-bounds index access in rare compiler tearing scenarios on VMs with a large number of vCPUs. This flaw was detected by Kernel Concurrency Sanitizer (KCSAN) and fixed by using atomic access macros. The vulnerability has a high severity with a CVSS score of 7.9 and affects multiple Linux kernel versions prior to fixed releases in the 5.4 and 5.15 series. A patch is available and should be applied to mitigate the risk.

References

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