---
title: "CVE-2026-89670: Linux Kernel - Use After Free"
description: "Linux kernel contains a use-after-free vulnerability in nfsd_file objects due to missing RCU locking around cmpxchg in nfsd_open_local_fh, letting attackers cause memory corruption or denial of service, exploit requires local code execution."
url: https://panop.io/threat-heartbeat/CVE-2026-89670/
---

# CVE-2026-89670 Linux Kernel - Use After Free

Linux kernel contains a use-after-free vulnerability in nfsd\_file objects due to missing RCU locking around cmpxchg in nfsd\_open\_local\_fh, letting attackers cause memory corruption or denial of service, exploit requires local code execution.

CVSS base score 7.8 /10

High

CISA KEV

Not listed

Public exploit

None known

EPSS

0.17% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89670)

## Details

Type

Use After Free

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:L/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 with the fix for proper RCU locking in nfsd\_open\_local\_fh.

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-2026-89670](https://nvd.nist.gov/vuln/detail/CVE-2026-89670)
- [https://git.kernel.org/stable/c/559570f91a7d4d199a72105e4980bef791f4cbf1](https://git.kernel.org/stable/c/559570f91a7d4d199a72105e4980bef791f4cbf1)
- [https://git.kernel.org/stable/c/58884694978a3d7d111edb433d7fd6a6c5af2f34](https://git.kernel.org/stable/c/58884694978a3d7d111edb433d7fd6a6c5af2f34)
- [https://git.kernel.org/stable/c/763c0bad872368304db718f79af7e93048885c67](https://git.kernel.org/stable/c/763c0bad872368304db718f79af7e93048885c67)

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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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