CVE-2023-40547 HIGH

CVE-2023-40547: Shim: rce in http boot support may lead to secure boot bypass

Weakness CWE-787
Published January 25, 2024
Last update June 26, 2026

CVSS base score

8.3/10
Attack vector Adjacent
Attack complexity High
Privileges required None
User interaction None
Confidentiality High
Integrity High

CVSS vector

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

What the vulnerability does

01Description

A remote code execution vulnerability was found in Shim. The Shim boot support trusts attacker-controlled values when parsing an HTTP response. This flaw allows an attacker to craft a specific malicious HTTP request, leading to a completely controlled out-of-bounds write primitive and complete system compromise. This flaw is only exploitable during the early boot phase, an attacker needs to perform a Man-in-the-Middle or compromise the boot server to be able to exploit this vulnerability successfully.

Key dates

02Disclosure timeline

January 25, 2024 CVE published
June 26, 2026 Record updated

Related vulnerabilities

04Related CVE