# CVE-2026-89658

## Summary

- **CVE ID:** CVE-2026-89658
- **Severity:** CRITICAL
- **CVSS Score:** 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- **CWE:** N/A
- **Published:** Sep 11, 2026
- **Last Modified:** Sep 13, 2026

## Description

In the Linux kernel, the following vulnerability has been resolved:

NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup

nfs40_clean_admin_revoked() takes a stateid reference under
clp->cl_lock, drops nn->client_lock, and calls
nfsd4_drop_revoked_stid(), which dereferences the stateid's client
through s->sc_client->cl_lock.  The stateid reference does not pin the
client, so a teardown racing the dropped lock can free the client
while nfsd4_drop_revoked_stid() is still using it.

This cleanup runs from the laundromat, so a periodic sweep can race
force_expire_client() driven by a write to the clients/<id>/ctl file.

Skip a client that is already expiring and otherwise pin it with
cl_rpc_users under client_lock before dropping the lock, matching
nfsd4_revoke_states().

## Affected Products

- Linux — Linux (d688d8585e6bea5e4e37f7497feea93b6b0a469c)
- Linux — Linux (6.9)
- Linux — Linux (0)
- Linux — Linux (6.12.109)
- Linux — Linux (6.18.50)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)

## References

- [CNA](https://git.kernel.org/stable/c/0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519)
- [CNA](https://git.kernel.org/stable/c/b413ec5b23e3445dc9c4f273116078e2d4747626)
- [CNA](https://git.kernel.org/stable/c/81cf7f1413862f87b078920c838460a6a88aa030)
- [CNA](https://git.kernel.org/stable/c/7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.61%
- **EPSS Percentile:** 47.6

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-18._