---
cve: "CVE-2026-89682"
severity: "HIGH"
cvss: 8.1
epss: "0.4%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-09-11 19:46:04"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-20T16:44:33+02:00"
---

# CVE-2026-89682

> 8.1 HIGH

## Beschreibung

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.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Hoch | good |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- Kernel ≥ 6.18.51
- Kernel ≥ 7.2.4

## Referenzen

- <https://git.kernel.org/stable/c/ba0ee9e04b7a0356c28d5a2fe445db675d24e572>
- <https://git.kernel.org/stable/c/cadc9036d5a8209f89e7026ddba7cfb1c716b03c>
- <https://git.kernel.org/stable/c/bbf13732f74351d21c5e0e8dd9bd8e1c48dc35d4>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-89682) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_