CVE-2026-31456: Linux kernel · mm/pagewalk: fix race between concurrent split and refault
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in 138ada1337b47cc5efb08e517674d46f86268274 : patch Linux kernel soon.
Data as of 5 Nov 2026, 22:32 UTC
Rated High by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- 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
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-05.
- Patch
- Available – fixed in 138ada1337b47cc5efb08e517674d46f86268274, 38ec58670a0c5fc1edabdeccd857e586b7b3f318, 9bbbebd94dd5be25ec8c899d46ef01b33d5d22c0 +1
Exploitation evidence
Disclosed: evidence found.
CVE published 22 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 5 Nov 2026.
What to do
Upgrade Linux kernel to 138ada1337b47cc5efb08e517674d46f86268274, 38ec58670a0c5fc1edabdeccd857e586b7b3f318, 9bbbebd94dd5be25ec8c899d46ef01b33d5d22c0 or 3b89863c3fa482912911cd65a12a3aeef662c250.
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– |
AI-suggested
A fix is available and has been applied in the Linux kernel. Users should update to the fixed kernel versions or apply the patch identified by the commit hashes provided. No additional mitigation steps are indicated beyond applying the official fix.
Description
A race condition in the Linux kernel's memory management subsystem (mm/pagewalk) has been fixed. The issue occurs when splitting a PUD entry concurrently with a refault operation, potentially causing a kernel crash (BUG) due to walking a PMD range that no longer exists. This can be triggered, for example, when reading numa_maps of a process during VFIO-PCI DMA setup on a large BAR. The fix involves validating the PUD entry with a stable snapshot and retrying the walk if the PUD is not present or is a leaf, preventing the race condition.
References
- git.kernel.org/stable/c/138ada1337b47cc5efb08e517674d46f86268274 (opens in a new tab)
- git.kernel.org/stable/c/38ec58670a0c5fc1edabdeccd857e586b7b3f318 (opens in a new tab)
- git.kernel.org/stable/c/9bbbebd94dd5be25ec8c899d46ef01b33d5d22c0 (opens in a new tab)
- git.kernel.org/stable/c/3b89863c3fa482912911cd65a12a3aeef662c250 (opens in a new tab)