---
title: "CVE-2026-89658: Linux Kernel - Use After Free"
description: "Linux kernel contains a use-after-free vulnerability in NFSD during NFSv4.0 revoked-state cleanup caused by improper client reference handling, letting attackers cause memory corruption, exploit requires race condition during client teardown."
url: https://panop.io/threat-heartbeat/CVE-2026-89658/
---

# CVE-2026-89658 Linux Kernel - Use After Free

Linux kernel contains a use-after-free vulnerability in NFSD during NFSv4.0 revoked-state cleanup caused by improper client reference handling, letting attackers cause memory corruption, exploit requires race condition during client teardown.

CVSS base score 9.8 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.62% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89658)

## Details

Type

Use After Free

Impact

Denial Of Service

CVSS vector

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

Published

11 September 2026

Updated

15 October 2026

## Vendor fix

Update to the latest Linux kernel version containing the fix for NFSD use-after-free.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-89658](https://nvd.nist.gov/vuln/detail/CVE-2026-89658)
- [https://git.kernel.org/stable/c/0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519](https://git.kernel.org/stable/c/0ae0d2b5c5a1b39c0b3c15d96b32a5b0c583d519)
- [https://git.kernel.org/stable/c/7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55](https://git.kernel.org/stable/c/7b4f8a1586c42d3afc3c0ac779af2db7ab1a5c55)
- [https://git.kernel.org/stable/c/81cf7f1413862f87b078920c838460a6a88aa030](https://git.kernel.org/stable/c/81cf7f1413862f87b078920c838460a6a88aa030)
- [https://git.kernel.org/stable/c/b413ec5b23e3445dc9c4f273116078e2d4747626](https://git.kernel.org/stable/c/b413ec5b23e3445dc9c4f273116078e2d4747626)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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