---
title: "CVE-2026-89689: Linux Kernel nfsd - Use After Free"
description: "Linux kernel nfsd contains a use-after-free vulnerability caused by improper freeing of session slots in nfsd4_sequence(), letting attackers cause memory corruption and potential denial of service, exploit requires crafted NFSv4 client requests."
url: https://panop.io/threat-heartbeat/CVE-2026-89689/
---

# CVE-2026-89689 Linux Kernel nfsd - Use After Free

Linux kernel nfsd contains a use-after-free vulnerability caused by improper freeing of session slots in nfsd4\_sequence(), letting attackers cause memory corruption and potential denial of service, exploit requires crafted NFSv4 client requests.

CVSS base score 9.8 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.65% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89689)

## 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 session slot freeing in nfsd4\_sequence.

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-2026-89689](https://nvd.nist.gov/vuln/detail/CVE-2026-89689)
- [https://git.kernel.org/stable/c/72d40b103bb03f0124d3a3c8f71a30cbafaf6afa](https://git.kernel.org/stable/c/72d40b103bb03f0124d3a3c8f71a30cbafaf6afa)
- [https://git.kernel.org/stable/c/b449b134e7762ddf98653a4b1d3e76d2d212ea64](https://git.kernel.org/stable/c/b449b134e7762ddf98653a4b1d3e76d2d212ea64)
- [https://git.kernel.org/stable/c/f5d22e372f4ac3eb287037a488c29691d52a6330](https://git.kernel.org/stable/c/f5d22e372f4ac3eb287037a488c29691d52a6330)

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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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