Insyde's Security Pledge

A vulnerability exists in SMM (System Management Mode) branch that registers a SWSMI handler that does not sufficiently check or validate the allocated buffer pointer(CommBuffer). This can be used by an attacker to corrupt data in SMRAM memory and even lead to arbitrary code execution.

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

This corresponds with CVE-2021-33627. It affects the driver FwBlockServiceSmm. This issue was discovered by Insyde engineering during an internal security review and reported on 25 May 2021. It was independently reported by Binarly (BRLY-2021-011) in September 2021.

Kernel 5.0, Version in 05.09.11
Kernel 5.1, Version in 05.17.11
Kernel 5.2, Version in 05.27.11
Kernel 5.3, Version in 05.36.11
Kernel 5.4, Version in 05.44.11
Kernel 5.5, Version in 05.52.11

Insyde Software would like to thank Binarly for reporting this issue.