---
title: "CVE-2026-99017: Linux Kernel - Privilege Escalation"
description: "Linux kernel contains a privilege escalation vulnerability caused by improper early boot stage detection in RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE, letting attackers bypass mitigation on vulnerable T-Head C9xx CPUs, exploit requires specific kernel configuration."
url: https://panop.io/threat-heartbeat/CVE-2026-99017/
---

# CVE-2026-99017 Linux Kernel - Privilege Escalation

Linux kernel contains a privilege escalation vulnerability caused by improper early boot stage detection in RISCV\_ALTERNATIVE\_EARLY for THEAD GHOSTWRITE, letting attackers bypass mitigation on vulnerable T-Head C9xx CPUs, exploit requires specific kernel configuration.

CVSS base score 7.0 /10

High

CISA KEV

Not listed

Public exploit

None known

EPSS

0.21% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-99017)

## Details

Type

Privilege Escalation

Impact

Privilege Escalation

CVSS vector

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

Published

23 October 2026

Updated

25 October 2026

## Vendor fix

Enable RISCV\_ALTERNATIVE\_EARLY selection in ERRATA\_THEAD\_GHOSTWRITE and update to the latest kernel version with the fix.

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-2026-99017](https://nvd.nist.gov/vuln/detail/CVE-2026-99017)
- [https://git.kernel.org/stable/c/298510bbc7c3017c0faf481c6ea66f1065b657b4](https://git.kernel.org/stable/c/298510bbc7c3017c0faf481c6ea66f1065b657b4)
- [https://git.kernel.org/stable/c/7fee577a2fa78b9a76da015beec1ccf978746ebb](https://git.kernel.org/stable/c/7fee577a2fa78b9a76da015beec1ccf978746ebb)
- [https://git.kernel.org/stable/c/fa465a7819ecbe5801b78c088d3cadaf2664b8ca](https://git.kernel.org/stable/c/fa465a7819ecbe5801b78c088d3cadaf2664b8ca)

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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

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

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