Critical 9.8Published Sep 11, 2026

CVE-2026-89662NFSD: Prevent lock owner use-after-free during client teardown

Updated under an hour ago (Oct 27, 2026, 4:10 PM ET)

Does this affect you?

It affects Linux. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for Linux

Exploited in the last 30 days

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 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

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

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.