CVE-2026-64561: Linux kernel · Race Condition
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 4 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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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
- git.kernel.org/stable/c/62ef67af1878fa2cd066642f2f59e33ade95f637 (opens in a new tab)
- git.kernel.org/stable/c/65c4f7a1028cf01a93a2762d679c289810ede990 (opens in a new tab)
- git.kernel.org/stable/c/35e77467610c4a37cb0ff54ee56b85f73b1f5700 (opens in a new tab)
- git.kernel.org/stable/c/0026dbb7de8ea76e97d6edf42fc3cc084564e2bf (opens in a new tab)
- git.kernel.org/stable/c/f3477a6a4164f15287444eda685b5f6405dbd1e5 (opens in a new tab)
- git.kernel.org/stable/c/bce0d3c26e2c761a4bf43c8949f333fc7374eb2d (opens in a new tab)
- git.kernel.org/stable/c/2abd5287f08319fa35764566b15c6e22cb1068db (opens in a new tab)
- github.com/V4bel/Zapscape (opens in a new tab)