---
title: "CVE-2026-89791: Linux Kernel - Use After Free"
description: "Linux kernel contains a use-after-free vulnerability in perf mmap() caused by a race condition between perf_mmap() revival and the last munmap(), letting local unprivileged users escalate privileges to root, exploit requires local access."
url: https://panop.io/threat-heartbeat/CVE-2026-89791/
---

# CVE-2026-89791 Linux Kernel - Use After Free

Linux kernel contains a use-after-free vulnerability in perf mmap() caused by a race condition between perf\_mmap() revival and the last munmap(), letting local unprivileged users escalate privileges to root, exploit requires local access.

CVSS base score 7.8 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.15% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89791)

## Details

Type

Use After Free

Impact

Privilege Escalation

CVSS vector

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

Published

16 September 2026

Updated

15 October 2026

## Vendor fix

Update to the latest Linux kernel version containing the fix for this race condition.

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-2026-89791](https://nvd.nist.gov/vuln/detail/CVE-2026-89791)
- [https://git.kernel.org/stable/c/929cb3b9dc818dd9fa89d510d4ff2b255e42badd](https://git.kernel.org/stable/c/929cb3b9dc818dd9fa89d510d4ff2b255e42badd)
- [https://git.kernel.org/stable/c/0c739f54f1c77f3a4643160cd2e031b6c2f2aab6](https://git.kernel.org/stable/c/0c739f54f1c77f3a4643160cd2e031b6c2f2aab6)
- [https://git.kernel.org/stable/c/58a8108bc73de0740d5b88150465d6690ea5f85f](https://git.kernel.org/stable/c/58a8108bc73de0740d5b88150465d6690ea5f85f)

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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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