# CVE-2026-89682

## Summary

- **CVE ID:** CVE-2026-89682
- **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: fix fcache_disposal UAF by inlining dispose state into nfsd_net

nfsd_file_dispose_list_delayed() defers fput() to nfsd service threads
via a per-net freeme queue, preventing the shrinker and GC worker from
bearing the cost of closing files (see ffb402596147).  However, the
queue lives in a separately-allocated struct nfsd_fcache_disposal that
is freed by nfsd_free_fcache_disposal_net() during per-net teardown.
The global shrinker, laundrette, and fsnotify callbacks can still be
inside nfsd_file_dispose_list_delayed() dereferencing that pointer,
causing a use-after-free.

Inline the spinlock and freeme list directly into struct nfsd_net (as
fcache_dispose_lock and fcache_dispose_list), eliminating the separately
allocated struct nfsd_fcache_disposal entirely.  These fields now have
the same lifetime as the net namespace itself, so there is no dangling
pointer to chase.

nfsd_file_cache_start_net() now just initializes the inline fields and
cannot fail due to allocation.  nfsd_file_cache_shutdown_net() drains
the inline list directly instead of freeing a separate struct.  The
alloc/free helpers are removed.

## Affected Products

- Linux — Linux (1463b38e7cf34d4cc60f41daff459ad807b2e408)
- Linux — Linux (e8f923e1e9fcc0832a12c8a2461792e5a9544c03)
- Linux — Linux (3bc94fb44f10ef852723e1aeaac6794c5ab16aec)
- Linux — Linux (5.10.220)
- Linux — Linux (5.15.154)
- Linux — Linux (5.17)
- 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/ba0ee9e04b7a0356c28d5a2fe445db675d24e572)
- [CNA](https://git.kernel.org/stable/c/cadc9036d5a8209f89e7026ddba7cfb1c716b03c)
- [CNA](https://git.kernel.org/stable/c/bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.40%
- **EPSS Percentile:** 33.6

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