---
title: "CVE-2026-89663: Linux Kernel - Use After Free"
description: "Linux kernel contains a use-after-free vulnerability in nfsd revoke paths caused by improper handling of copy-notify stateids references, letting attackers cause memory corruption or kernel crashes, exploit requires concurrent revoke and state management operations."
url: https://panop.io/threat-heartbeat/CVE-2026-89663/
---

# CVE-2026-89663 Linux Kernel - Use After Free

Linux kernel contains a use-after-free vulnerability in nfsd revoke paths caused by improper handling of copy-notify stateids references, letting attackers cause memory corruption or kernel crashes, exploit requires concurrent revoke and state management operations.

CVSS base score 8.8 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.46% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89663)

## Details

Type

Use After Free

Impact

Denial Of Service, Privilege Escalation

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/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 copy-notify stateids revoke handling.

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-2026-89663](https://nvd.nist.gov/vuln/detail/CVE-2026-89663)
- [https://git.kernel.org/stable/c/b56d2c5f01cddbeca7d11cce81d97db4ec9a464f](https://git.kernel.org/stable/c/b56d2c5f01cddbeca7d11cce81d97db4ec9a464f)
- [https://git.kernel.org/stable/c/ff8a3cff02b92b2a82f1a9876038fcf953ae9c25](https://git.kernel.org/stable/c/ff8a3cff02b92b2a82f1a9876038fcf953ae9c25)
- [https://git.kernel.org/stable/c/06a62f6dbc60791f4229c6950b1eec6b18df9af1](https://git.kernel.org/stable/c/06a62f6dbc60791f4229c6950b1eec6b18df9af1)
- [https://git.kernel.org/stable/c/5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0d](https://git.kernel.org/stable/c/5f00e0ab4de45d4f9e4bd0883cf2517acf63fc0d)
- [https://git.kernel.org/stable/c/a1fca0f7bbb7b100a39c7ba8dd7922c87c4237a3](https://git.kernel.org/stable/c/a1fca0f7bbb7b100a39c7ba8dd7922c87c4237a3)
- [https://git.kernel.org/stable/c/caddbeffab1eaba1d2bcf5ceda35547863466705](https://git.kernel.org/stable/c/caddbeffab1eaba1d2bcf5ceda35547863466705)
- [https://git.kernel.org/stable/c/3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7](https://git.kernel.org/stable/c/3b0c3595db99bb4bebd7c8aa8a36f3c50e411bb7)
- [https://git.kernel.org/stable/c/6b8149448cdcb476fba4559d1ecc247efee9971b](https://git.kernel.org/stable/c/6b8149448cdcb476fba4559d1ecc247efee9971b)

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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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