{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-64437","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-07-19T15:36:31.788Z","datePublished":"2026-07-25T08:51:11.072Z","dateUpdated":"2026-08-17T04:55:38.646Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-17T04:55:38.646Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free of a deferred file_lock on SMB2_CLOSE then SMB2_CANCEL\n\nCommit f580d27e8928 (\"ksmbd: fix use-after-free of a deferred file_lock on\ndouble SMB2_CANCEL\") made smb2_cancel() skip a work whose state is\nKSMBD_WORK_CANCELLED, so its cancel_fn cannot be fired a second time. But\nKSMBD_WORK has three states (ACTIVE, CANCELLED, CLOSED), and the same\nfreeing producer path is reached for CLOSED too:\n\n  SMB2_CLOSE on the locking handle -> set_close_state_blocked_works() sets\n  the deferred work's state to KSMBD_WORK_CLOSED and wakes the smb2_lock()\n  worker. The worker takes the non-ACTIVE early-exit, locks_free_lock()s\n  the file_lock and, because the state is not KSMBD_WORK_CANCELLED, takes\n  the STATUS_RANGE_NOT_LOCKED branch with \"goto out2\" -- which, like the\n  cancelled branch, skips release_async_work(). The work stays on\n  conn->async_requests with a live cancel_fn = smb2_remove_blocked_lock\n  pointing at the freed file_lock.\n\nA subsequent SMB2_CANCEL for the same AsyncId then passes the\nKSMBD_WORK_CANCELLED-only guard (its state is KSMBD_WORK_CLOSED), so\nsmb2_cancel() fires cancel_fn again over the freed file_lock -- the same\nuse-after-free fixed, via SMB2_CLOSE instead of a first SMB2_CANCEL:\n\n  BUG: KASAN: slab-use-after-free in __locks_delete_block\n    __locks_delete_block\n    locks_delete_block\n    ksmbd_vfs_posix_lock_unblock\n    smb2_remove_blocked_lock\n    smb2_cancel                 <- 2nd SMB2_CANCEL fires cancel_fn\n    handle_ksmbd_work\n  Allocated by ...: locks_alloc_lock <- smb2_lock\n  Freed by ...:     locks_free_lock  <- smb2_lock (non-ACTIVE early-exit)\n  ... cache file_lock_cache of size 192\n\nReproduced on mainline 7.1-rc7 (which already contains f580d27e8928) with\nKASAN by an authenticated SMB client; the double-SMB2_CANCEL control is\nsilent on that kernel, so the splat is attributable to the CLOSE trigger.\n\nOnly an ACTIVE deferred work may have its cancel_fn fired: both terminal\nstates (CANCELLED and CLOSED) reach the smb2_lock() early-exit that frees\nthe file_lock and skips release_async_work(). Guard on KSMBD_WORK_ACTIVE\nso any non-active work is skipped."}],"metrics":[{"cvssV3_1":{"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"},"scenarios":[{"lang":"en","value":"AV:N - ksmbd processes attacker-supplied SMB2 requests over TCP port 445, so the complete vulnerable path is remotely network-reachable.\nAC:L - The attacker controls the conflicting file handles, deferred LOCK, CLOSE, and CANCEL requests and can pipeline or repeat them to win the cleanup race without relying on victim-controlled conditions.\nPR:L - The sequence is post-authentication: LOCK and CLOSE require a valid SMB session, authorized tree connection, and usable file handle, but only ordinary share-user rights and no administrative capabilities.\nUI:N - No victim action is required because the authenticated SMB client can create the conflicting locks and send the complete triggering sequence.\nS:U - The corruption occurs within the host kernel serving SMB and does not inherently cross a separate virtualization, sandbox, or IOMMU security authority.\nC:H - The stale 192-byte file_lock is dereferenced through attacker-timed slab reuse, including linked-list and waitqueue pointers, making kernel-memory disclosure reasonably exploitable.\nI:H - Operations such as list unlinking and waitqueue handling on the reclaimed object can corrupt kernel pointers and potentially provide arbitrary writes or control-flow hijacking.\nA:H - The confirmed slab use-after-free can cause a kernel oops or panic, and the remote client can repeatedly trigger the sequence."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/smb2pdu.c"],"versions":[{"version":"b7063c7426ea5a4d15e01b60538718765392f49d","lessThan":"a796ba4e61d5e14e07b79a359faac69f8f9b22a3","status":"affected","versionType":"git"},{"version":"0da2e073f9cbf4985a0fd9acb71bc5ff599f8afd","lessThan":"b8e274e69ab09222c7a552c7c0c1eef9ce627fc1","status":"affected","versionType":"git"},{"version":"89ae9df09d2c1fb4a4eb495c113a7ce1dca34147","lessThan":"ddb9239828336b36d8a3ef5943fdffb2f55b6508","status":"affected","versionType":"git"},{"version":"14d2eee0193ac3cd1bf3d014373449f0b8d35d6d","lessThan":"94083db751930b1540ddff2b54d4677549c57f81","status":"affected","versionType":"git"},{"version":"f580d27e8928828693df44ba2db0fffdbe11dfea","lessThan":"12c36c99655f325befe50c26842f7deca414c381","status":"affected","versionType":"git"},{"version":"f580d27e8928828693df44ba2db0fffdbe11dfea","lessThan":"10f293a07f9e10e988b0ae44e2e99c631f5a68e0","status":"affected","versionType":"git"},{"version":"2b2eda2821cff1d1b5a423b6ee7d8fc6fbc8e694","status":"affected","versionType":"git"},{"version":"6.1.176","lessThan":"6.1.178","status":"affected","versionType":"semver"},{"version":"6.6.143","lessThan":"6.6.145","status":"affected","versionType":"semver"},{"version":"6.12.94","lessThan":"6.12.96","status":"affected","versionType":"semver"},{"version":"6.18.36","lessThan":"6.18.39","status":"affected","versionType":"semver"},{"version":"7.0.13","lessThan":"7.1","status":"affected","versionType":"semver"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/server/smb2pdu.c"],"versions":[{"version":"7.1","status":"affected"},{"version":"0","lessThan":"7.1","status":"unaffected","versionType":"semver"},{"version":"6.1.178","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.145","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.96","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.39","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.4","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1.176","versionEndExcluding":"6.1.178"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6.143","versionEndExcluding":"6.6.145"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12.94","versionEndExcluding":"6.12.96"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18.36","versionEndExcluding":"6.18.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.1.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.1","versionEndExcluding":"7.2"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0.13"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/a796ba4e61d5e14e07b79a359faac69f8f9b22a3"},{"url":"https://git.kernel.org/stable/c/b8e274e69ab09222c7a552c7c0c1eef9ce627fc1"},{"url":"https://git.kernel.org/stable/c/ddb9239828336b36d8a3ef5943fdffb2f55b6508"},{"url":"https://git.kernel.org/stable/c/94083db751930b1540ddff2b54d4677549c57f81"},{"url":"https://git.kernel.org/stable/c/12c36c99655f325befe50c26842f7deca414c381"},{"url":"https://git.kernel.org/stable/c/10f293a07f9e10e988b0ae44e2e99c631f5a68e0"}],"title":"ksmbd: fix use-after-free of a deferred file_lock on SMB2_CLOSE then SMB2_CANCEL","x_generator":{"engine":"bippy-1.2.0"}}}}