---
title: "CVE-2026-89664: Linux Kernel NFSd - Resource Leak"
description: "Linux kernel contains a resource leak vulnerability in NFS server (nfsd) caused by missing release of OPEN-decoded POSIX ACLs in nfsd4 operations, letting attackers cause resource leaks, exploit requires sending malformed OPEN compound requests with valid POSIX ACL attributes."
url: https://panop.io/threat-heartbeat/CVE-2026-89664/
---

# CVE-2026-89664 Linux Kernel NFSd - Resource Leak

Linux kernel contains a resource leak vulnerability in NFS server (nfsd) caused by missing release of OPEN-decoded POSIX ACLs in nfsd4 operations, letting attackers cause resource leaks, exploit requires sending malformed OPEN compound requests with valid POSIX ACL attributes.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.49% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89664)

## Details

Type

Resource Leak

Impact

Denial Of Service

CVSS vector

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

Published

11 September 2026

Updated

15 October 2026

## Vendor fix

Update to the latest Linux kernel version containing the fix for nfsd OPEN-decoded POSIX ACL release.

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-2026-89664](https://nvd.nist.gov/vuln/detail/CVE-2026-89664)
- [https://git.kernel.org/stable/c/5b3a7d7c23c071efe12dd1bc1d2e5f97c4892921](https://git.kernel.org/stable/c/5b3a7d7c23c071efe12dd1bc1d2e5f97c4892921)
- [https://git.kernel.org/stable/c/8215892993ea9f5231da4fa9eb42428a286fce8b](https://git.kernel.org/stable/c/8215892993ea9f5231da4fa9eb42428a286fce8b)

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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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