CVE-2026-23401: In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Drop/zap existing present S

Q: How do I fix CVE-2026-23401?

linux kernel: upgrade to 5.15.203, 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11. Exact commands for each OS are on this page.

Q: Is CVE-2026-23401 being exploited?

CVE-2026-23401 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-23401 affect?

CVE-2026-23401 affects linux kernel. Severity is medium (CVSS 5.5). In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE When installing an emulated MMIO SPTE, do so *after* dropping/zapping the existing SPTE (if i

Q: How urgent is CVE-2026-23401?

Priority 26/100. On your watchlist

Routine

MEDIUM 5.5WATCHLISTUPGRADE

CVE-2026-23401 is a medium-severity flaw (CVSS 5.5) 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/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE When installing an emulated MMIO SPTE, do so *after* dropping/zapping the existing SPTE (if it's shadow-present). While commit a54aa15c6bda3 was right about it being impossible to convert a shadow-present SPTE to an MMIO SPTE due to a _guest_ write, it failed to account for writes to guest memory that

Why this priority

On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 92%)
CISA exploited list	No
Weakness	CWE-416
Published	2026-04-01
Last modified	2026-07-15

Publisher (CNA): kernel.org · Vendor: linux

Last updated 2026-07-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-01 09:16 UTCPublished CVE record published
2026-07-15 02:18 UTCUpdated Record last modified

linux linux kernel UPGRADE

Affected: >= 5.13.1 and < 5.15.203 · >= 5.16 and < 6.1.168 · >= 6.2 and < 6.6.131 · >= 6.7 and < 6.12.80 · >= 6.13 and < 6.18.21 · >= 6.19 and < 6.19.11 · 5.13 · 7.0 rc1

Fixed in: 5.15.203, 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11

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-2026-23401?

linux kernel: upgrade to 5.15.203, 6.1.168, 6.6.131, 6.12.80, 6.18.21, 6.19.11. Exact commands for each OS are on this page.

Is CVE-2026-23401 being exploited?

CVE-2026-23401 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-2026-23401 affect?

CVE-2026-23401 affects linux kernel. Severity is medium (CVSS 5.5). In the Linux kernel, the following vulnerability has been resolved: KVM: x86/mmu: Drop/zap existing present SPTE even when creating an MMIO SPTE When installing an emulated MMIO SPTE, do so *after* dropping/zapping the existing SPTE (if i

How urgent is CVE-2026-23401?

Priority 26/100. On your watchlist

Software pages

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References

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