{"id":"CVE-2026-64396","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation\n\nWhen a blocking byte-range lock request is deferred in the\nFILE_LOCK_DEFERRED path, ksmbd re…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation\n\nWhen a blocking byte-range lock request is deferred in the\nFILE_LOCK_DEFERRED path, ksmbd re…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 5.15, < 6.1.178","linux_kernel >= 6.2, < 6.6.145","linux_kernel >= 6.7, < 6.12.96","linux_kernel >= 6.13, < 6.18.39","linux_kernel >= 6.19, < 7.1.4"],"patched":["linux_kernel 7.1.4"],"published":"2026-07-25","updated":"2026-09-04","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-64396","references":[{"url":"https://git.kernel.org/stable/c/367c42a611fe488b7b03f1f6737f4dee0e8b20a2","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/463bbd79698513af4dad50fe1c573825f297ca2e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5aa1cb01155f96824003baf7997cdf1f150caba3","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5c75275c0fc9a2deb0d8f5604edcb16f288171c8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7703fd9aba1f2483c8e55f9ff73b7663e0761ed9","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/d20d1c8ba5765d1d12eefc0aee6385ab3f240e1e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"tags":["nvd"],"epss":0.00435,"epssPercentile":0.37147,"ingestedAt":"2026-09-05T13:39:57.690Z","slug":"CVE-2026-64396","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix UAF of struct file_lock in SMB2_LOCK deferred-lock cancellation\n\nWhen a blocking byte-range lock request is deferred in the\nFILE_LOCK_DEFERRED path, ksmbd registers the asynchronous work into\nthe connection's async_requests list via setup_async_work(). The cancel\ncallback smb2_remove_blocked_lock() holds a reference to the flock.\n\nIf the lock waiter is subsequently woken up but the work state is no\nlonger KSMBD_WORK_ACTIVE (e.g., due to a concurrent cancellation), the\ncleanup path calls locks_free_lock(flock) without dequeuing the work from\nthe async_requests list. Concurrently, smb2_cancel() walks the list\nunder conn->request_lock and invokes the cancel callback, which then\ndereferences the already freed 'flock'. This leads to a slab-use-after-free\ninside __wake_up_common.\n\nFix this by restructuring the cleanup logic after the worker returns\nfrom ksmbd_vfs_posix_lock_wait(). Move list_del(&smb_lock->llist) and\nrelease_async_work(work) to the top of the cleanup block. This guarantees\nthat the async work is completely dequeued and serialized under\nconn->request_lock before locks_free_lock(flock) is called, rendering\nthe flock unreachable for any concurrent smb2_cancel().\n\n## Affected\n\n- `linux_kernel >= 5.15, < 6.1.178`\n- `linux_kernel >= 6.2, < 6.6.145`\n- `linux_kernel >= 6.7, < 6.12.96`\n- `linux_kernel >= 6.13, < 6.18.39`\n- `linux_kernel >= 6.19, < 7.1.4`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.1.4`","depth":"twilight","depthScore":48,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}