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VulnerabilityPublished Updated

CVE-2026-64561: Linux kernel · Race Condition

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 8.8 High · fixed in f3477a6a4164f15287444eda685b5f6405dbd1e5 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
8.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 19% 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 f3477a6a4164f15287444eda685b5f6405dbd1e5, bce0d3c26e2c761a4bf43c8949f333fc7374eb2d, 65c4f7a1028cf01a93a2762d679c289810ede990 +4
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 4 Aug 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
  • ≥ f95eec9bed76d42194c23153cb1cc8f186bf91cb, < f3477a6a4164f15287444eda685b5f6405dbd1e5
Fixed in
  • f3477a6a4164f15287444eda685b5f6405dbd1e5
LinuxLinuxAffected
  • ≥ f95eec9bed76d42194c23153cb1cc8f186bf91cb, < bce0d3c26e2c761a4bf43c8949f333fc7374eb2d
Fixed in
  • bce0d3c26e2c761a4bf43c8949f333fc7374eb2d
LinuxLinuxAffected
  • ≥ f95eec9bed76d42194c23153cb1cc8f186bf91cb, < 65c4f7a1028cf01a93a2762d679c289810ede990
Fixed in
  • 65c4f7a1028cf01a93a2762d679c289810ede990
LinuxLinuxAffected
  • ≥ f95eec9bed76d42194c23153cb1cc8f186bf91cb, < 62ef67af1878fa2cd066642f2f59e33ade95f637
Fixed in
  • 62ef67af1878fa2cd066642f2f59e33ade95f637
LinuxLinuxAffected
  • ≥ f95eec9bed76d42194c23153cb1cc8f186bf91cb, < 35e77467610c4a37cb0ff54ee56b85f73b1f5700
Fixed in
  • 35e77467610c4a37cb0ff54ee56b85f73b1f5700
LinuxLinuxAffected
  • ≥ f95eec9bed76d42194c23153cb1cc8f186bf91cb, < 0026dbb7de8ea76e97d6edf42fc3cc084564e2bf
Fixed in
  • 0026dbb7de8ea76e97d6edf42fc3cc084564e2bf

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: x86: Check for invalid/obsolete root *after* making MMU pages available Check for a "stale" page fault, i.e. for an invalid and/or obsolete root, after making MMU pages available for the shadow MMU. If reclaiming shadow pages zaps an in-use root, i.e. marks it invalid, then KVM will attempt to map memory into an invalid root. On its own, populating an invalid root is "fine", but because child shadow pages inherit their parent's role, any children created during the map/fetch will be created as invalid pages, thus violating KVM's invariant that invalid pages are never on the list of active MMU pages. Note, the underlying flaw has existed since KVM first started tracking invalid roots in 2008 (commit 2e53d63acba7, "KVM: MMU: ignore zapped root pagetables"), but the true badness only came along in 2020 (Linux 5.9) with the invariant that invalid shadow pages can't be on the list of active pages. Note #2, inheriting role.invalid when creating child shadow pages is also far from ideal; that flaw will be addressed separately.

References

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