SB20261023146 - Improper initialization in Linux kernel riscv

Description

This security bulletin contains information about 1 vulnerability.

1) Improper initialization (CVE-ID: CVE-2026-99017)

CWE-ID: CWE-665 - Improper Initialization

CVSSv4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

The vulnerability allows a local user to potentially bypass intended CPU security protections on vulnerable T-Head C9xx systems.

The vulnerability exists due to improper initialization of the CPU vulnerability state in the Linux kernel's RISC-V T-Head Ghostwrite errata handling when early boot alternatives are not executed. A local user can potentially use the still-enabled xtheadvector extension on a vulnerable CPU to bypass intended CPU security protections.

The affected configuration has ERRATA_THEAD_GHOSTWRITE=y and ERRATA_THEAD_MAE=n.

Remediation

Install update from vendor's website.

References

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