---
cve: "CVE-2026-89690"
severity: "HIGH"
cvss: 7.8
epss: "16%"
vendor: "Linux"
kev: false
exploited: false
published: "2026-09-11 20:19:56"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-17T11:57:18+02:00"
---

# CVE-2026-89690

> 7.8 HIGH

## Beschreibung

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

nfsd: defer vfree of compound ops to fix rpc_status UAF

The rpc_status netlink dumpit walks every in-flight svc_rqst under
rcu_read_lock and, for NFSv4 requests, reads opnums out of
args->ops[]. But args->ops is a separate vmalloc buffer freed
synchronously by vfree() in nfsd4_release_compoundargs() at the end
of every compound. The dumpit's rcu_read_lock pins the svc_rqst
struct itself (freed via kfree_rcu), but nothing defers the vfree
of the ops buffer across the RCU grace period. A concurrent compound
completion can therefore free the buffer while the dumpit is reading
it — a use-after-free on vmalloc memory.

The trailing seqcount recheck (smp_load_acquire of rq_status_counter)
cannot undo a load that already retired against freed memory.

Fix by replacing vfree(args->ops) with kvfree_rcu_mightsleep(), which
defers the free until after an RCU grace period. This makes the
existing rcu_read_lock in the dumpit sufficient to protect the read.
The tradeoff is that completed compound ops buffers (up to
200 * sizeof(struct nfsd4_op)) persist in memory slightly longer,
across one grace period, before being reclaimed.

## CVSS-Vektor

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

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

## Patch verfügbar (OSV)

- Kernel ≥ 6.12.109
- Kernel ≥ 6.18.50
- Kernel ≥ 7.2.4

## Referenzen

- <https://git.kernel.org/stable/c/48f72aff24f7a7329209dc6cbc27c869f3e3595c>
- <https://git.kernel.org/stable/c/6703199f4d7e7f37d6a726a849eb358e8fae72fb>
- <https://git.kernel.org/stable/c/19413ccc45070a7270b9e25c2a258daf7f91de42>
- <https://git.kernel.org/stable/c/fca26a3fc19ed02278aa2a150af82d43db0302cb>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-89690) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_