---
title: "CVE-2026-89708: Linux Kernel - Use After Free"
description: "Linux kernel contains a use-after-free vulnerability in nfsd caused by improper handling of cl_cb_session during session teardown, letting attackers cause memory corruption or denial of service, exploit requires triggering session destruction with inflight callbacks."
url: https://panop.io/threat-heartbeat/CVE-2026-89708/
---

# CVE-2026-89708 Linux Kernel - Use After Free

Linux kernel contains a use-after-free vulnerability in nfsd caused by improper handling of cl\_cb\_session during session teardown, letting attackers cause memory corruption or denial of service, exploit requires triggering session destruction with inflight callbacks.

CVSS base score 9.8 /10

Critical

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.44% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89708)

## 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 nfsd RCU-protected cl\_cb\_session.

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-2026-89708](https://nvd.nist.gov/vuln/detail/CVE-2026-89708)
- [https://git.kernel.org/stable/c/01c5d5f58a5db9b0ee5afba2e49d3157788687b2](https://git.kernel.org/stable/c/01c5d5f58a5db9b0ee5afba2e49d3157788687b2)
- [https://git.kernel.org/stable/c/13bdd486c3aad4fc19e6d8b9c3556a4b4c190b25](https://git.kernel.org/stable/c/13bdd486c3aad4fc19e6d8b9c3556a4b4c190b25)
- [https://git.kernel.org/stable/c/f164eb52b6f3cbf40f07fe379f9f421f88e02f76](https://git.kernel.org/stable/c/f164eb52b6f3cbf40f07fe379f9f421f88e02f76)
- [https://git.kernel.org/stable/c/2775ec1d617e665eab71ce0f13ab1f7959713a2b](https://git.kernel.org/stable/c/2775ec1d617e665eab71ce0f13ab1f7959713a2b)

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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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