{"id":"CVE-2026-53198","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-53198","generatedAt":"2026-10-28T02:23:03.546Z","title":"In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL A deferred byte-range lock (an SMB2_LOCK that blocks) registers an async work on conn->async_requests via…","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free of a deferred file_lock on double SMB2_CANCEL\n\nA deferred byte-range lock (an SMB2_LOCK that blocks) registers an async work on\nconn->async_requests via setup_async_work(), with cancel_fn =\nsmb2_remove_blocked_lock and cancel_argv[0] pointing at the struct file_lock.\n\nWhen the request is cancelled, the worker frees the file_lock with\nlocks_free_lock() and takes the cancelled early-exit, which \"goto out\"s and never\nreaches release_async_work() -- the only site that unlinks the work from\nconn->async_requests and clears cancel_fn/cancel_argv. The work therefore stays\nmatchable on async_requests with a live cancel_fn pointing at the freed file_lock,\nuntil connection teardown finally runs release_async_work().\n\nsmb2_cancel() fires cancel_fn unconditionally with no state guard, so a second\nSMB2_CANCEL for the same AsyncId, arriving in that window, re-runs\nsmb2_remove_blocked_lock() on the freed file_lock -- a slab use-after-free:\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 (cancelled branch)\n  ... cache file_lock_cache of size 192\n\nReproduced on mainline with KASAN by an authenticated SMB client.\n\nSkip a work whose state is already KSMBD_WORK_CANCELLED so its cancel callback\ncannot be fired a second time.","published":"2026-06-25T09:16:37.000Z","lastModified":"2026-10-15T02:20:04.000Z","status":"Modified","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":8.8,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-416"],"affected":["linux/linux kernel"],"epss":{"score":0.00445,"percentile":0.38448,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.45%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/0da2e073f9cbf4985a0fd9acb71bc5ff599f8afd","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/14d2eee0193ac3cd1bf3d014373449f0b8d35d6d","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/2b2eda2821cff1d1b5a423b6ee7d8fc6fbc8e694","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/89ae9df09d2c1fb4a4eb495c113a7ce1dca34147","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/b7063c7426ea5a4d15e01b60538718765392f49d","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/f580d27e8928828693df44ba2db0fffdbe11dfea","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html","source":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-53198","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}