CVE-2026-64514

CVE CVE-2026-64514EUVD EUVD-2026-48858Published 2026-07-25T08:52:05.000Z

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: userfaultfd: gate must_wait writability check on pte_present() userfaultfd_must_wait() and userfaultfd_huge_must_wait() read the PTE without taking the page table lock and then apply pte_write() / huge_pte_write() to it. Those accessors decode bits from the present encoding only; on a swap or migration entry they read the offset bits that happen to share the same position and return an undefined result. The intent of the check is "is this fault still WP-blocked?". A non-marker swap entry means the page is in transit -- the userfault context the original fault delivered against is no longer the same, and the swap-in or migration completion path will re-deliver a fresh fault if userspace still needs to handle it. Worst case under the current code the garbage write bit says "wait", and the thread stays asleep until a UFFDIO_WAKE that may never arrive. Gate the writability check on pte_present() so the lockless re-check only inspects present-PTE bits when the entry is actually present. The non-present, non-marker case returns "don't wait" and lets the fault path retry.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux 369cd2121be440543280b91056de187f625d0dbb <60d696a037eeeedfb57756dfe7ec08a1587c8631; patch: 7.2-rc1; patch: 6.1.178; patch: 0; 369cd2121be440543280b91056de187f625d0dbb <8e80af52db652fbc41320eee45a4f73bc029faf2; 369cd2121be440543280b91056de187f625d0dbb <29e6f952c5fb7dc1d6b90fe5b7f36063d44ddae0; patch: 7.1.4; 4.11; 369cd2121be440543280b91056de187f625d0dbb <5f4dbdb0a87596214076b20b94f2b71b522170b3; patch: 6.18.39; 369cd2121be440543280b91056de187f625d0dbb <a6e9a4939e359599701b1da351e84f72e021443a; 369cd2121be440543280b91056de187f625d0dbb <710183888174639a15fcec16cd1af766b8480bb7; patch: 5.15.212; patch: 6.12.96; 369cd2121be440543280b91056de187f625d0dbb <d4026417e8184d13850a0bad4d96ceb6ed9f7152; patch: 6.6.145; patch: 5.10.261; 369cd2121be440543280b91056de187f625d0dbb <a5700a4c1c9099ac2ac73fe8a09cf059972e0d2f

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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