# CVE-2026-89667

## Summary

- **CVE ID:** CVE-2026-89667
- **Severity:** HIGH
- **CVSS Score:** 8.1 (CVSS:3.1/AV:N/AC:H/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: close shrinker/GC/fsnotify vs per-net shutdown race in filecache

The shrinker, GC worker, and fsnotify/lease callbacks can unhash an
nfsd_file from the rhashtable and then call
nfsd_file_dispose_list_delayed() to move it to the per-net dispose list.
If nfsd_file_cache_shutdown_net() runs concurrently, its rhashtable walk
misses the already-unhashed file, and its drain of the per-net dispose
list can run before the file has been queued.  The file then sits on
the per-net list with no thread to drain it, leaking both the file and
its associated state.

The GC worker and shrinker already hold nfsd_gc_lock while walking the
LRU, but in the original code they release it before calling
nfsd_file_dispose_list_delayed().  The fsnotify/lease path
(nfsd_file_close_inode) has no synchronization at all.

Fix this by:

  1. Widening nfsd_gc_lock in both nfsd_file_gc() and nfsd_file_lru_scan()
     to cover the nfsd_file_dispose_list_delayed() call.

  2. Wrapping nfsd_file_close_inode() in nfsd_gc_lock so that all three
     callers of nfsd_file_dispose_list_delayed() hold the lock.

  3. Adding a spin_lock/unlock(nfsd_gc_lock) barrier in
     nfsd_file_cache_shutdown_net() after the purge, so that any
     in-progress disposal has fully completed before the per-net list
     is drained.

All operations inside the lock are non-sleeping (rhashtable lookups,
atomic bit/refcount ops, list moves, svc_wake_up), so the spinlock is
appropriate.

## Affected Products

- Linux — Linux (ffb402596147ac583f3464ff5c48feb9423e3838)
- Linux — Linux (6.9)
- Linux — Linux (0)
- Linux — Linux (6.18.51)
- Linux — Linux (7.2.4)
- Linux — Linux (7.3-rc1)

## References

- [CNA](https://git.kernel.org/stable/c/6d6b9f6a75c3767250e9c23ace4e384ab8f7843e)
- [CNA](https://git.kernel.org/stable/c/08af9593e2b472fd98c00faf1bf03bdbb7203477)
- [CNA](https://git.kernel.org/stable/c/40162cfea79b9510380decfdd1795b754dc9f972)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.51%
- **EPSS Percentile:** 42.5

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