{"api_version":"1","generated_at":"2026-07-26T22:33:03+00:00","cve":"CVE-2026-64437","urls":{"html":"https://cve.report/CVE-2026-64437","api":"https://cve.report/api/cve/CVE-2026-64437.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64437","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64437"},"summary":{"title":"ksmbd: fix use-after-free of a deferred file_lock on SMB2_CLOSE then SMB2_CANCEL","description":"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.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-25 10:17:28","updated_at":"2026-07-25 10:17:28"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/94083db751930b1540ddff2b54d4677549c57f81","name":"https://git.kernel.org/stable/c/94083db751930b1540ddff2b54d4677549c57f81","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/b8e274e69ab09222c7a552c7c0c1eef9ce627fc1","name":"https://git.kernel.org/stable/c/b8e274e69ab09222c7a552c7c0c1eef9ce627fc1","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/10f293a07f9e10e988b0ae44e2e99c631f5a68e0","name":"https://git.kernel.org/stable/c/10f293a07f9e10e988b0ae44e2e99c631f5a68e0","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/12c36c99655f325befe50c26842f7deca414c381","name":"https://git.kernel.org/stable/c/12c36c99655f325befe50c26842f7deca414c381","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/ddb9239828336b36d8a3ef5943fdffb2f55b6508","name":"https://git.kernel.org/stable/c/ddb9239828336b36d8a3ef5943fdffb2f55b6508","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/a796ba4e61d5e14e07b79a359faac69f8f9b22a3","name":"https://git.kernel.org/stable/c/a796ba4e61d5e14e07b79a359faac69f8f9b22a3","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64437","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64437","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected b7063c7426ea5a4d15e01b60538718765392f49d a796ba4e61d5e14e07b79a359faac69f8f9b22a3 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 0da2e073f9cbf4985a0fd9acb71bc5ff599f8afd b8e274e69ab09222c7a552c7c0c1eef9ce627fc1 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 89ae9df09d2c1fb4a4eb495c113a7ce1dca34147 ddb9239828336b36d8a3ef5943fdffb2f55b6508 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 14d2eee0193ac3cd1bf3d014373449f0b8d35d6d 94083db751930b1540ddff2b54d4677549c57f81 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f580d27e8928828693df44ba2db0fffdbe11dfea 12c36c99655f325befe50c26842f7deca414c381 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected f580d27e8928828693df44ba2db0fffdbe11dfea 10f293a07f9e10e988b0ae44e2e99c631f5a68e0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 2b2eda2821cff1d1b5a423b6ee7d8fc6fbc8e694 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.1.176 6.1.178 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6.143 6.6.145 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.94 6.12.96 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.18.36 6.18.39 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.0.13 7.1 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.1","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.178 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.145 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.96 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.39 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1.4 7.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2-rc1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"64437","cve":"CVE-2026-64437","epss":"0.002150000","percentile":"0.119910000","score_date":"2026-07-25","updated_at":"2026-07-26 00:12:33"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["fs/smb/server/smb2pdu.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"a796ba4e61d5e14e07b79a359faac69f8f9b22a3","status":"affected","version":"b7063c7426ea5a4d15e01b60538718765392f49d","versionType":"git"},{"lessThan":"b8e274e69ab09222c7a552c7c0c1eef9ce627fc1","status":"affected","version":"0da2e073f9cbf4985a0fd9acb71bc5ff599f8afd","versionType":"git"},{"lessThan":"ddb9239828336b36d8a3ef5943fdffb2f55b6508","status":"affected","version":"89ae9df09d2c1fb4a4eb495c113a7ce1dca34147","versionType":"git"},{"lessThan":"94083db751930b1540ddff2b54d4677549c57f81","status":"affected","version":"14d2eee0193ac3cd1bf3d014373449f0b8d35d6d","versionType":"git"},{"lessThan":"12c36c99655f325befe50c26842f7deca414c381","status":"affected","version":"f580d27e8928828693df44ba2db0fffdbe11dfea","versionType":"git"},{"lessThan":"10f293a07f9e10e988b0ae44e2e99c631f5a68e0","status":"affected","version":"f580d27e8928828693df44ba2db0fffdbe11dfea","versionType":"git"},{"status":"affected","version":"2b2eda2821cff1d1b5a423b6ee7d8fc6fbc8e694","versionType":"git"},{"lessThan":"6.1.178","status":"affected","version":"6.1.176","versionType":"semver"},{"lessThan":"6.6.145","status":"affected","version":"6.6.143","versionType":"semver"},{"lessThan":"6.12.96","status":"affected","version":"6.12.94","versionType":"semver"},{"lessThan":"6.18.39","status":"affected","version":"6.18.36","versionType":"semver"},{"lessThan":"7.1","status":"affected","version":"7.0.13","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["fs/smb/server/smb2pdu.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"7.1"},{"lessThan":"7.1","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.178","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.145","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.96","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.39","versionType":"semver"},{"lessThanOrEqual":"7.1.*","status":"unaffected","version":"7.1.4","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.2-rc1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.178","versionStartIncluding":"6.1.176","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.145","versionStartIncluding":"6.6.143","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.96","versionStartIncluding":"6.12.94","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.39","versionStartIncluding":"6.18.36","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1.4","versionStartIncluding":"7.1","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2-rc1","versionStartIncluding":"7.1","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"7.0.13","vulnerable":true}],"negate":false,"operator":"OR"}]}],"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."}],"providerMetadata":{"dateUpdated":"2026-07-25T08:51:11.072Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"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"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64437","datePublished":"2026-07-25T08:51:11.072Z","dateReserved":"2026-07-19T15:36:31.788Z","dateUpdated":"2026-07-25T08:51:11.072Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-25 10:17:28","lastModifiedDate":"2026-07-25 10:17:28","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64437","Ordinal":"1","Title":"ksmbd: fix use-after-free of a deferred file_lock on SMB2_CLOSE ","CVE":"CVE-2026-64437","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64437","Ordinal":"1","NoteData":"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.","Type":"Description","Title":"ksmbd: fix use-after-free of a deferred file_lock on SMB2_CLOSE "}]}}}