CVE-2026-31588

Guest-to-host compromise via stale MMIO write pointer

Published Apr 24, 2026 · Updated Apr 24, 2026

Use-after-free in Linux Kernel KVM x86 MMIO emulation allows guest OS users to compromise the host through crafted MMIO writes. A split write leaves an MMIO fragment pointing to an initiating task's on-stack value, and a later KVM_RUN dereferences that pointer after the stack can be freed or reused. The write must be eight bytes or smaller and cross two MMIO pages; successful triggering can disclose or corrupt host kernel memory or crash the host.

CVSS severity8.8
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux Kernel KVM x86 MMIO emulation allows guest OS users to compromise the host through crafted MMIO writes. A split write leaves an MMIO fragment pointing to an initiating task's on-stack value, and a later KVM_RUN dereferences that pointer after the stack can be freed or reused. The write must be eight bytes or smaller and cross two MMIO pages; successful triggering can disclose or corrupt host kernel memory or crash the host.

The record

CVE
CVE-2026-31588
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, T1611
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <22d2ff69d487a32a8b88f9c970120fc2daa08a77
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2b83d91e9ae92fe1258d7040a32430bbb3bb7d6e
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3a7b6d75c8f85b09dea893f64a85a356bcf6c3fe
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b5a02d37eb0739f462fa12df449ab9b3480c783b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <22d2ff69d487a32a8b88f9c970120fc2daa08a77; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2b83d91e9ae92fe1258d7040a32430bbb3bb7d6e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3a7b6d75c8f85b09dea893f64a85a356bcf6c3fe; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b5a02d37eb0739f462fa12df449ab9b3480c783b

Published CVSS scores

8.8Linux kernel CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1611Escape to Host

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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