CVE-2026-89662NFSD: Prevent lock owner use-after-free during client teardown
- 9.8CriticalCVSS base score
- 0.69%Exploitation in 30 daysEPSS · top 47% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By Linux
Published
- 38 days later
· 38 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Received | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.69% · top 47% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
- affected 68ef3bc3166468678d5e1fdd216628c35bd1186f – < 42d7954b0a1907d4ef122aef94561952a033cdc3
- affected 68ef3bc3166468678d5e1fdd216628c35bd1186f – < bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a
- affected 68ef3bc3166468678d5e1fdd216628c35bd1186f – < b8bad5a11416b26cc7fd4b18fba46d75ff636558
- affected 68ef3bc3166468678d5e1fdd216628c35bd1186f – < 1ce74d1b7770e69735e8f8e509807af4ff9c8ee7
- affected 68ef3bc3166468678d5e1fdd216628c35bd1186f – < a6ead6fff3a7d03e49845f048f7000a2e0d34431
- affected 68ef3bc3166468678d5e1fdd216628c35bd1186f – < 4804c58f73a80d12df1de323bf97a164f6ee8743
- affected 68ef3bc3166468678d5e1fdd216628c35bd1186f – < 8cf4ff0a7c083dd5e0067f517d63979b74b66649
- affected 68ef3bc3166468678d5e1fdd216628c35bd1186f – < 5e2fa29d223a9a1e6a948e40b109d09081d1decd
- affected e294c4c2d33b7307a89cdf31bec08a112d6a9297
- affected 797bfd05d4040fbf766198b3cfcc1838002cc890
- affected 0f44e9da465ea259b6c9f31a627f3c50a16e1679
- affected 4.9.91 – < 4.10
- affected 4.14.31 – < 4.15
- affected 4.15.14 – < 4.16
- affected 4.16
- unaffected < 4.16
- unaffected 5.10.270 – ≤ 5.10.*
- unaffected 5.15.221 – ≤ 5.15.*
- unaffected 6.1.188 – ≤ 6.1.*
- unaffected 6.6.157 – ≤ 6.6.*
- unaffected 6.12.109 – ≤ 6.12.*
- unaffected 6.18.50 – ≤ 6.18.*
- unaffected 7.2.4 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References8
- https://git.kernel.org/stable/c/42d7954b0a1907d4ef122aef94561952a033cdc3 (opens in a new tab)
- https://git.kernel.org/stable/c/bb38ff8b4dafbbd1781ad37cd96722fdf2cd972a (opens in a new tab)
- https://git.kernel.org/stable/c/b8bad5a11416b26cc7fd4b18fba46d75ff636558 (opens in a new tab)
- https://git.kernel.org/stable/c/1ce74d1b7770e69735e8f8e509807af4ff9c8ee7 (opens in a new tab)
- https://git.kernel.org/stable/c/a6ead6fff3a7d03e49845f048f7000a2e0d34431 (opens in a new tab)
- https://git.kernel.org/stable/c/4804c58f73a80d12df1de323bf97a164f6ee8743 (opens in a new tab)
- https://git.kernel.org/stable/c/8cf4ff0a7c083dd5e0067f517d63979b74b66649 (opens in a new tab)
- https://git.kernel.org/stable/c/5e2fa29d223a9a1e6a948e40b109d09081d1decd (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-76574 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-89662)Record last updated .