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        "name": "Kernel"
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  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64437.json"
  },
  "details": "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 -\u003e 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-\u003easync_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                 \u003c- 2nd SMB2_CANCEL fires cancel_fn\n    handle_ksmbd_work\n  Allocated by ...: locks_alloc_lock \u003c- smb2_lock\n  Freed by ...:     locks_free_lock  \u003c- 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.",
  "id": "CVE-2026-64437",
  "modified": "2026-07-28T03:56:00.414059027Z",
  "published": "2026-07-25T08:51:11.072Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/10f293a07f9e10e988b0ae44e2e99c631f5a68e0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/12c36c99655f325befe50c26842f7deca414c381"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/94083db751930b1540ddff2b54d4677549c57f81"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a796ba4e61d5e14e07b79a359faac69f8f9b22a3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b8e274e69ab09222c7a552c7c0c1eef9ce627fc1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ddb9239828336b36d8a3ef5943fdffb2f55b6508"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64437.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64437"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.8.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "ksmbd: fix use-after-free of a deferred file_lock on SMB2_CLOSE then SMB2_CANCEL"
}