CVE-2026-89662NFSD: Prevent lock owner use-after-free during client teardown
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: NFSD: Prevent lock owner use-after-free during client teardown __destroy_client() releases a client's open owners, but a lock owner whose only reference is a blocked lock (nbl) stays on cl_ownerstr_hashtbl. client_has_state() does not count a bare owner, so DESTROY_CLIENTID can reach __destroy_client() with such owners present. __destroy_client() then walks the table, calling remove_blocked_locks() on each owner without a reference. Freeing a blocked lock drops the owner reference held via flc_owner. The per-net laundromat reaps blocked locks from nn->blocked_locks_lru independently of client state. The two paths share blocked_locks_lock only for the list splice, not the owner's lifetime. The laundromat therefore frees the owner as __destroy_client() dereferences it, a NULL dereference in remove_blocked_locks(). nfsd4_release_lockowner() holds a reference across the same call; __destroy_client() does not. Hold cl_lock across the walk, taking a reference and unhashing each owner, then drop it before remove_blocked_locks() and nfs4_put_stateowner(), which take blocked_locks_lock and cl_lock.
- CVSS
- 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Received
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | 68ef3bc3166468678d5e1fdd216628c35bd1186f builds before 42d7954b0a1907d4ef122aef94561952a033cdc3; from 68ef3bc3166468678d5e1fdd216628c35bd1186f before bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a; from 68ef3bc3166468678d5e1fdd216628c35bd1186f before b8bad5a11416b26cc7fd4b18fba46d75ff636558; 68ef3bc3166468678d5e1fdd216628c35bd1186f builds before 1ce74d1b7770e69735e8f8e509807af4ff9c8ee7; from 68ef3bc3166468678d5e1fdd216628c35bd1186f before a6ead6fff3a7d03e49845f048f7000a2e0d34431; from 68ef3bc3166468678d5e1fdd216628c35bd1186f before 4804c58f73a80d12df1de323bf97a164f6ee8743; 68ef3bc3166468678d5e1fdd216628c35bd1186f builds before 8cf4ff0a7c083dd5e0067f517d63979b74b66649; 68ef3bc3166468678d5e1fdd216628c35bd1186f builds before 5e2fa29d223a9a1e6a948e40b109d09081d1decd; and 6 more ranges | CNA record |
References
- https://git.kernel.org/stable/c/42d7954b0a1907d4ef122aef94561952a033cdc3
- https://git.kernel.org/stable/c/bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a
- https://git.kernel.org/stable/c/b8bad5a11416b26cc7fd4b18fba46d75ff636558
- https://git.kernel.org/stable/c/1ce74d1b7770e69735e8f8e509807af4ff9c8ee7
- https://git.kernel.org/stable/c/a6ead6fff3a7d03e49845f048f7000a2e0d34431
- https://git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743
- https://git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649
- https://git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.