{"id":"CVE-2026-64514","summary":"userfaultfd: gate must_wait writability check on pte_present()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: gate must_wait writability check on pte_present()\n\nuserfaultfd_must_wait() and userfaultfd_huge_must_wait() read the PTE\nwithout taking the page table lock and then apply pte_write() /\nhuge_pte_write() to it.  Those accessors decode bits from the present\nencoding only; on a swap or migration entry they read the offset bits that\nhappen to share the same position and return an undefined result.\n\nThe intent of the check is \"is this fault still WP-blocked?\".  A\nnon-marker swap entry means the page is in transit -- the userfault\ncontext the original fault delivered against is no longer the same, and\nthe swap-in or migration completion path will re-deliver a fresh fault if\nuserspace still needs to handle it.  Worst case under the current code the\ngarbage write bit says \"wait\", and the thread stays asleep until a\nUFFDIO_WAKE that may never arrive.\n\nGate the writability check on pte_present() so the lockless re-check only\ninspects present-PTE bits when the entry is actually present.  The\nnon-present, non-marker case returns \"don't wait\" and lets the fault path\nretry.","modified":"2026-07-27T04:03:22.903721964Z","published":"2026-07-25T08:52:05.878Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64514.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/29e6f952c5fb7dc1d6b90fe5b7f36063d44ddae0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5f4dbdb0a87596214076b20b94f2b71b522170b3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/60d696a037eeeedfb57756dfe7ec08a1587c8631"},{"type":"WEB","url":"https://git.kernel.org/stable/c/710183888174639a15fcec16cd1af766b8480bb7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8e80af52db652fbc41320eee45a4f73bc029faf2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a5700a4c1c9099ac2ac73fe8a09cf059972e0d2f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a6e9a4939e359599701b1da351e84f72e021443a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d4026417e8184d13850a0bad4d96ceb6ed9f7152"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64514.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64514"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"369cd2121be440543280b91056de187f625d0dbb"},{"fixed":"a5700a4c1c9099ac2ac73fe8a09cf059972e0d2f"},{"fixed":"d4026417e8184d13850a0bad4d96ceb6ed9f7152"},{"fixed":"29e6f952c5fb7dc1d6b90fe5b7f36063d44ddae0"},{"fixed":"5f4dbdb0a87596214076b20b94f2b71b522170b3"},{"fixed":"a6e9a4939e359599701b1da351e84f72e021443a"},{"fixed":"60d696a037eeeedfb57756dfe7ec08a1587c8631"},{"fixed":"710183888174639a15fcec16cd1af766b8480bb7"},{"fixed":"8e80af52db652fbc41320eee45a4f73bc029faf2"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64514.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.11.0"},{"fixed":"5.10.261"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.212"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.178"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.145"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.96"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.39"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64514.json"}}],"schema_version":"1.7.5"}