---
title: "CVE-2026-89706: Linux kernel nfsd - Broken Access Control"
description: "Linux kernel nfsd contains a broken access control vulnerability caused by failure to reset write verifier on async COPY writeback failure, letting NFS clients incorrectly assume data durability, exploit requires NFS client interaction."
url: https://panop.io/threat-heartbeat/CVE-2026-89706/
---

# CVE-2026-89706 Linux kernel nfsd - Broken Access Control

Linux kernel nfsd contains a broken access control vulnerability caused by failure to reset write verifier on async COPY writeback failure, letting NFS clients incorrectly assume data durability, exploit requires NFS client interaction.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.53% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89706)

## Details

Type

Broken Access Control

Impact

Broken Access Control

CVSS vector

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

Published

11 September 2026

Updated

15 October 2026

## Vendor fix

Update to the Linux kernel version containing the fix for async COPY writeback failure.

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-2026-89706](https://nvd.nist.gov/vuln/detail/CVE-2026-89706)
- [https://git.kernel.org/stable/c/31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0](https://git.kernel.org/stable/c/31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0)
- [https://git.kernel.org/stable/c/591134e059e3456180244a826d6917cdc183140b](https://git.kernel.org/stable/c/591134e059e3456180244a826d6917cdc183140b)
- [https://git.kernel.org/stable/c/bf0cd31a9abcb728c17d79b4c2cc533612a8b6af](https://git.kernel.org/stable/c/bf0cd31a9abcb728c17d79b4c2cc533612a8b6af)
- [https://git.kernel.org/stable/c/f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9](https://git.kernel.org/stable/c/f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9)
- [https://git.kernel.org/stable/c/6b13d26cc21b6320a3c61d5e4cee2ce9a589b181](https://git.kernel.org/stable/c/6b13d26cc21b6320a3c61d5e4cee2ce9a589b181)
- [https://git.kernel.org/stable/c/8a08ffe73eb2aa6bc6f88763da7e2b55bab6493a](https://git.kernel.org/stable/c/8a08ffe73eb2aa6bc6f88763da7e2b55bab6493a)
- [https://git.kernel.org/stable/c/c6d2f6372c7e0f76b9c148ff7696aec64da0b5b7](https://git.kernel.org/stable/c/c6d2f6372c7e0f76b9c148ff7696aec64da0b5b7)
- [https://git.kernel.org/stable/c/cc5f7cef0659a27c13dd33edd8e2f79257b095c6](https://git.kernel.org/stable/c/cc5f7cef0659a27c13dd33edd8e2f79257b095c6)

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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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