---
title: "CVE-2026-89903: Linux kernel - Broken Access Control"
description: "Linux kernel contains a broken access control vulnerability in LoongArch rethook trampoline caused by saving and restoring percpu base register across CPU migrations, letting attackers cause scheduler and timer corruption under heavy kretprobe load, exploit requires kretprobe usage on LoongArch."
url: https://panop.io/threat-heartbeat/CVE-2026-89903/
---

# CVE-2026-89903 Linux kernel - Broken Access Control

Linux kernel contains a broken access control vulnerability in LoongArch rethook trampoline caused by saving and restoring percpu base register across CPU migrations, letting attackers cause scheduler and timer corruption under heavy kretprobe load, exploit requires kretprobe usage on LoongArch.

CVSS base score 7.8 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.18% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-89903)

## Details

Type

Broken Access Control

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

16 September 2026

Updated

15 October 2026

## Vendor fix

Update to the latest Linux kernel version containing the fix for the LoongArch rethook trampoline issue.

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-2026-89903](https://nvd.nist.gov/vuln/detail/CVE-2026-89903)
- [https://git.kernel.org/stable/c/c048b0a3c0836c4b1bef4b51d355d27090bf6790](https://git.kernel.org/stable/c/c048b0a3c0836c4b1bef4b51d355d27090bf6790)
- [https://git.kernel.org/stable/c/c3f2feace5e4f4b01b68b9f947b19adb4155c32e](https://git.kernel.org/stable/c/c3f2feace5e4f4b01b68b9f947b19adb4155c32e)
- [https://git.kernel.org/stable/c/266ffc92e68593759adfe3d58f188773d32782c3](https://git.kernel.org/stable/c/266ffc92e68593759adfe3d58f188773d32782c3)
- [https://git.kernel.org/stable/c/8f15e95b438bc6b3c9f23a33c9a0d0678ebd1dc8](https://git.kernel.org/stable/c/8f15e95b438bc6b3c9f23a33c9a0d0678ebd1dc8)
- [https://git.kernel.org/stable/c/a03b5e7483ad2c33ba5dd2adb8552e84bfee8fe2](https://git.kernel.org/stable/c/a03b5e7483ad2c33ba5dd2adb8552e84bfee8fe2)

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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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