Answer in brief
CVE-2026-89662 records a Unknown severity vulnerability in NFSD: Prevent lock owner use-after-free during client teardown. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=68ef3bc3166468678d5e1fdd216628c35bd1186f <a6ead6fff3a7d03e49845f048f7000a2e0d34431 || >=68ef3bc3166468678d5e1fdd216628c35bd1186f <4804c58f73a80d12df1de323bf97a164f6ee8743 || >=68ef3bc3166468678d5e1fdd216628c35bd1186f <8cf4ff0a7c083dd5e0067f517d63979b74b66649 || >=68ef3bc3166468678d5e1fdd216628c35bd1186f <5e2fa29d223a9a1e6a948e40b109d09081d1decd || e294c4c2d33b7307a89cdf31bec08a112d6a9297 || 797bfd05d4040fbf766198b3cfcc1838002cc890 || 0f44e9da465ea259b6c9f31a627f3c50a16e1679 || >=4.9.91 <4.10 || >=4.14.31 <4.15 || >=4.15.14 <4.16 | a6ead6fff3a7d03e49845f048f7000a2e0d34431, 4804c58f73a80d12df1de323bf97a164f6ee8743, 8cf4ff0a7c083dd5e0067f517d63979b74b66649, 5e2fa29d223a9a1e6a948e40b109d09081d1decd, 4.10, 4.15, 4.16 |
| Linux/Linuxgeneric | 4.16 | Not reported |
Published upstream
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 11, 2026
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.
Quoted source text, attributed separately from HOL analysis.