{"api_version":"1","generated_at":"2026-07-28T12:20:07+00:00","cve":"CVE-2026-64396","urls":{"html":"https://cve.report/CVE-2026-64396","api":"https://cve.report/api/cve/CVE-2026-64396.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64396","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64396"},"summary":{"title":"ksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation\n\nWhen a blocking byte-range lock request is deferred in the\nFILE_LOCK_DEFERRED path, ksmbd registers the asynchronous work into\nthe connection's async_requests list via setup_async_work(). The cancel\ncallback smb2_remove_blocked_lock() holds a reference to the flock.\n\nIf the lock waiter is subsequently woken up but the work state is no\nlonger KSMBD_WORK_ACTIVE (e.g., due to a concurrent cancellation), the\ncleanup path calls locks_free_lock(flock) without dequeuing the work from\nthe async_requests list. Concurrently, smb2_cancel() walks the list\nunder conn->request_lock and invokes the cancel callback, which then\ndereferences the already freed 'flock'. This leads to a slab-use-after-free\ninside __wake_up_common.\n\nFix this by restructuring the cleanup logic after the worker returns\nfrom ksmbd_vfs_posix_lock_wait(). Move list_del(&smb_lock->llist) and\nrelease_async_work(work) to the top of the cleanup block. This guarantees\nthat the async work is completely dequeued and serialized under\nconn->request_lock before locks_free_lock(flock) is called, rendering\nthe flock unreachable for any concurrent smb2_cancel().","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-25 10:17:23","updated_at":"2026-07-27 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Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64396","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 367c42a611fe488b7b03f1f6737f4dee0e8b20a2 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 7703fd9aba1f2483c8e55f9ff73b7663e0761ed9 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 463bbd79698513af4dad50fe1c573825f297ca2e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 5aa1cb01155f96824003baf7997cdf1f150caba3 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 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the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation\n\nWhen a blocking byte-range lock request is deferred in the\nFILE_LOCK_DEFERRED path, ksmbd registers the asynchronous work into\nthe connection's async_requests list via setup_async_work(). The cancel\ncallback smb2_remove_blocked_lock() holds a reference to the flock.\n\nIf the lock waiter is subsequently woken up but the work state is no\nlonger KSMBD_WORK_ACTIVE (e.g., due to a concurrent cancellation), the\ncleanup path calls locks_free_lock(flock) without dequeuing the work from\nthe async_requests list. Concurrently, smb2_cancel() walks the list\nunder conn->request_lock and invokes the cancel callback, which then\ndereferences the already freed 'flock'. This leads to a slab-use-after-free\ninside __wake_up_common.\n\nFix this by restructuring the cleanup logic after the worker returns\nfrom ksmbd_vfs_posix_lock_wait(). Move list_del(&smb_lock->llist) and\nrelease_async_work(work) to the top of the cleanup block. This guarantees\nthat the async work is completely dequeued and serialized under\nconn->request_lock before locks_free_lock(flock) is called, rendering\nthe flock unreachable for any concurrent smb2_cancel()."}],"metrics":[{"cvssV3_1":{"baseScore":8.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"}}],"providerMetadata":{"dateUpdated":"2026-07-27T05:00:26.968Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/367c42a611fe488b7b03f1f6737f4dee0e8b20a2"},{"url":"https://git.kernel.org/stable/c/7703fd9aba1f2483c8e55f9ff73b7663e0761ed9"},{"url":"https://git.kernel.org/stable/c/463bbd79698513af4dad50fe1c573825f297ca2e"},{"url":"https://git.kernel.org/stable/c/5aa1cb01155f96824003baf7997cdf1f150caba3"},{"url":"https://git.kernel.org/stable/c/5c75275c0fc9a2deb0d8f5604edcb16f288171c8"},{"url":"https://git.kernel.org/stable/c/d20d1c8ba5765d1d12eefc0aee6385ab3f240e1e"}],"title":"ksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64396","datePublished":"2026-07-25T08:50:40.993Z","dateReserved":"2026-07-19T15:36:31.785Z","dateUpdated":"2026-07-27T05:00:26.968Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-25 10:17:23","lastModifiedDate":"2026-07-27 05:16:46","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":2.8,"impactScore":5.9}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64396","Ordinal":"1","Title":"ksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock ca","CVE":"CVE-2026-64396","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64396","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation\n\nWhen a blocking byte-range lock request is deferred in the\nFILE_LOCK_DEFERRED path, ksmbd registers the asynchronous work into\nthe connection's async_requests list via setup_async_work(). The cancel\ncallback smb2_remove_blocked_lock() holds a reference to the flock.\n\nIf the lock waiter is subsequently woken up but the work state is no\nlonger KSMBD_WORK_ACTIVE (e.g., due to a concurrent cancellation), the\ncleanup path calls locks_free_lock(flock) without dequeuing the work from\nthe async_requests list. Concurrently, smb2_cancel() walks the list\nunder conn->request_lock and invokes the cancel callback, which then\ndereferences the already freed 'flock'. This leads to a slab-use-after-free\ninside __wake_up_common.\n\nFix this by restructuring the cleanup logic after the worker returns\nfrom ksmbd_vfs_posix_lock_wait(). Move list_del(&smb_lock->llist) and\nrelease_async_work(work) to the top of the cleanup block. This guarantees\nthat the async work is completely dequeued and serialized under\nconn->request_lock before locks_free_lock(flock) is called, rendering\nthe flock unreachable for any concurrent smb2_cancel().","Type":"Description","Title":"ksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock ca"}]}}}