---
title: "CVE-2026-78118: Linux Kernel - Use After Free"
description: "The kernel helper z_waitq_head() in kernel/include/wait_q.h contains a use-after-free and out-of-bounds write caused by improper locking on SMP systems in kernel/timer.c, letting unprivileged local attackers cause kernel crashes or state corruption, exploit requires multi-CPU system and local code execution with precise timing."
url: https://panop.io/threat-heartbeat/CVE-2026-78118/
---

# CVE-2026-78118 Linux Kernel - Use After Free

The kernel helper z\_waitq\_head() in kernel/include/wait\_q.h contains a use-after-free and out-of-bounds write caused by improper locking on SMP systems in kernel/timer.c, letting unprivileged local attackers cause kernel crashes or state corruption, exploit requires multi-CPU system and local code execution with precise timing.

CVSS base score 7.0 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-78118)

## Details

Type

Use After Free

Impact

Denial Of Service

CVSS vector

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

Published

21 October 2026

Updated

22 October 2026

Weakness

[CWE-362](https://cwe.mitre.org/data/definitions/362.html)

## Vendor fix

Update to the latest kernel version with the fix that adds proper locking in z\_waitq\_head and timer expiration handler.

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-2026-78118](https://nvd.nist.gov/vuln/detail/CVE-2026-78118)
- [https://github.com/zephyrproject-rtos/zephyr/commit/a9b21fb354e8468dd15db307c3e599dc68b7ef33](https://github.com/zephyrproject-rtos/zephyr/commit/a9b21fb354e8468dd15db307c3e599dc68b7ef33)
- [https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-gm6w-pv43-m3vf](https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-gm6w-pv43-m3vf)

[← All CVEs](https://panop.io/threat-heartbeat/)

## 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

Panop answers these inside your environment, for this CVE and every other finding.

[Book a demo](https://panop.io/demo)