CVE-2026-64514: Linux kernel · userfaultfd: gate must_wait writability check on pte_present()
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 3 Nov 2026, 18:43 UTC
Rated Medium by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Thin evidence
One scorer or noneExploitation evidence
Disclosed: evidence found.
CVE published 25 Jul 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 3 Nov 2026.
What to do
AI-suggested
A fix has been implemented in the Linux kernel that gates the writability check on pte_present(), ensuring correct behavior. Users should apply the official kernel updates that include this fix. No other mitigation is indicated.
Description
CVE-2026-64514 is a vulnerability in the Linux kernel's userfaultfd subsystem where writability checks on page table entries (PTEs) are performed without proper locking, leading to undefined results when the PTE is not present but instead a swap or migration entry. This can cause threads to wait indefinitely for a wake event that may never occur.
References
- git.kernel.org/stable/c/a5700a4c1c9099ac2ac73fe8a09cf059972e0d2f (opens in a new tab)
- git.kernel.org/stable/c/d4026417e8184d13850a0bad4d96ceb6ed9f7152 (opens in a new tab)
- git.kernel.org/stable/c/29e6f952c5fb7dc1d6b90fe5b7f36063d44ddae0 (opens in a new tab)
- git.kernel.org/stable/c/5f4dbdb0a87596214076b20b94f2b71b522170b3 (opens in a new tab)
- git.kernel.org/stable/c/a6e9a4939e359599701b1da351e84f72e021443a (opens in a new tab)
- git.kernel.org/stable/c/60d696a037eeeedfb57756dfe7ec08a1587c8631 (opens in a new tab)
- git.kernel.org/stable/c/710183888174639a15fcec16cd1af766b8480bb7 (opens in a new tab)
- git.kernel.org/stable/c/8e80af52db652fbc41320eee45a4f73bc029faf2 (opens in a new tab)