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VulnerabilityPublished Updated

CVE-2026-31588: Linux kernel · Use After Free

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 8.8 High · fixed in dc6a6c3db3a4eca7e747cfc46e22c08d016c68f7 : patch Linux kernel soon.

Data as of 26 Oct 2026, 15:59 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in dc6a6c3db3a4eca7e747cfc46e22c08d016c68f7, b5a02d37eb0739f462fa12df449ab9b3480c783b, 52570e73d48f1c73836d37e594667117b4c2a5a8 +6
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Apr 2026

  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
LinuxLinuxAffected
  • ≥ f78146b0f9230765c6315b2e14f56112513389ad, < dc6a6c3db3a4eca7e747cfc46e22c08d016c68f7
Fixed in
  • dc6a6c3db3a4eca7e747cfc46e22c08d016c68f7
LinuxLinuxAffected
  • ≥ f78146b0f9230765c6315b2e14f56112513389ad, < b5a02d37eb0739f462fa12df449ab9b3480c783b
Fixed in
  • b5a02d37eb0739f462fa12df449ab9b3480c783b
LinuxLinuxAffected
  • ≥ f78146b0f9230765c6315b2e14f56112513389ad, < 52570e73d48f1c73836d37e594667117b4c2a5a8
Fixed in
  • 52570e73d48f1c73836d37e594667117b4c2a5a8
LinuxLinuxAffected
  • ≥ f78146b0f9230765c6315b2e14f56112513389ad, < 4569c66dd9e94a22cd0796b6514a8b25ffff16a1
Fixed in
  • 4569c66dd9e94a22cd0796b6514a8b25ffff16a1
LinuxLinuxAffected
  • ≥ f78146b0f9230765c6315b2e14f56112513389ad, < 22d2ff69d487a32a8b88f9c970120fc2daa08a77
Fixed in
  • 22d2ff69d487a32a8b88f9c970120fc2daa08a77
LinuxLinuxAffected
  • ≥ f78146b0f9230765c6315b2e14f56112513389ad, < 019d0bd32b9a4646ba35d904907452039e2db700
Fixed in
  • 019d0bd32b9a4646ba35d904907452039e2db700

AI-suggested

A fix for this vulnerability is available and has been merged into the Linux kernel in multiple commits. Users should update their Linux kernel to a version that includes these fixes. No additional mitigation steps are required beyond applying the official patch.

Description

CVE-2026-31588 is a use-after-free vulnerability in the Linux kernel's KVM x86 MMIO emulation. It occurs when servicing emulated MMIO writes that split page boundaries and involve small write values stored on the stack. This flaw can lead to referencing freed stack memory during MMIO completion, potentially causing memory corruption or crashes. The issue has been fixed by copying small write values into a scratch field in the MMIO fragment instead of referencing the original stack variable directly.

References

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