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CVE-2026-31588: In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Use scratch field in MMIO fragm

38
Routine
HIGH 8.8WATCHLISTUPGRADE

CVE-2026-31588 is a high-severity flaw (CVSS 8.8) affecting linux kernel. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Use scratch field in MMIO fragment to hold small write values When exiting to userspace to service an emulated MMIO write, copy the to-be-written value to a scratch field in the MMIO fragment if the size of the data payload is 8 bytes or less, i.e. can fit in a single chunk, instead of pointing the fragment directly at the source value. This fixes a class of use-afte

Why this priority

  • High severity
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score8.8 (High)
Attack vectorLocal
Attack complexityLow
Privileges neededLow
User interactionNone
EPSS exploit chance0.2% (top 91%)
CISA exploited listNo
WeaknessCWE-416
Published2026-04-24
Last modified2026-10-19
Publisher (CNA): kernel.org · Vendor: linux

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Last updated 2026-10-19 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

linux linux kernel UPGRADE
Affected: >= 3.5 and < 6.6.136 · >= 6.7 and < 6.12.83 · >= 6.13 and < 6.18.24 · >= 6.19 and < 6.19.14 · >= 7.0 and < 7.0.1
Fixed in: 6.6.136, 6.12.83, 6.18.24, 6.19.14, 7.0.1
Safe to downgrade to: no unaffected older release
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-31588?

linux kernel: upgrade to 6.6.136, 6.12.83, 6.18.24, 6.19.14, 7.0.1. Exact commands for each OS are on this page.

Is CVE-2026-31588 being exploited?

CVE-2026-31588 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-31588 affect?

CVE-2026-31588 affects linux kernel. Severity is high (CVSS 8.8). In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Use scratch field in MMIO fragment to hold small write values When exiting to userspace to service an emulated MMIO write, copy the to-be-written value to a scr

How urgent is CVE-2026-31588?

Priority 38/100. High severity; On your watchlist

Software pages

Linux kernel vulnerabilities

Related CVEs

References

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