{ "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" } } } }