CVE-2021-42060 in InsydeH2O
Summary
by MITRE • 02/03/2022
An issue was discovered in Insyde InsydeH2O Kernel 5.0 through 05.08.41, Kernel 5.1 through 05.16.41, Kernel 5.2 before 05.23.22, and Kernel 5.3 before 05.32.22. An Int15ServiceSmm SMM callout vulnerability allows an attacker to hijack execution flow of code running in System Management Mode. Exploiting this issue could lead to escalating privileges to SMM.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 11/04/2025
The vulnerability identified as CVE-2021-42060 represents a critical flaw in the Insyde InsydeH2O Kernel firmware implementations across multiple versions. This issue specifically affects the Int15ServiceSmm SMM callout mechanism, which operates within the System Management Mode of computer systems. The vulnerability resides in the kernel's handling of SMM calls, creating a potential attack vector that could allow malicious actors to manipulate the execution flow of code running in the most privileged system mode. The affected versions span across kernel releases 5.0 through 05.08.41, 5.1 through 05.16.41, 5.2 before 05.23.22, and 5.3 before 05.32.22, indicating a widespread issue within the firmware ecosystem that could impact numerous devices and systems. This flaw falls under the category of firmware-level vulnerabilities that can have severe implications for system security and integrity.
The technical nature of this vulnerability stems from improper validation and handling of SMM callout requests within the Int15ServiceSmm service. When an attacker can manipulate the execution flow through this mechanism, they gain the ability to redirect code execution within the SMM context, which operates with the highest privilege level in the system. The SMM is designed to handle critical system functions and maintain system stability, making any compromise of this mode particularly dangerous. The vulnerability allows for privilege escalation to SMM, which means that an attacker who successfully exploits this issue could gain complete control over the system's firmware operations, potentially enabling persistent backdoors, rootkit installation, or complete system compromise. This represents a fundamental breach of the system's security model as SMM is intended to be isolated from normal operating system execution and protected from unauthorized access.
The operational impact of CVE-2021-42060 extends far beyond typical software vulnerabilities due to its location within the firmware layer where the system's most privileged operations occur. An attacker who successfully exploits this vulnerability could establish persistent access to the system, manipulate hardware operations, and potentially hide malicious activities from normal system monitoring and detection mechanisms. The attack surface is particularly concerning because SMM operates outside the normal operating system execution context, making it difficult for traditional security tools to detect or prevent such attacks. This vulnerability could enable attackers to create persistent backdoors that survive operating system reinstallation, system resets, or even complete hardware replacement. The implications are severe for enterprise environments, government systems, and any infrastructure where firmware-level attacks could compromise the entire security posture of the organization. The vulnerability also aligns with the ATT&CK framework's SMM persistence techniques, specifically targeting the system's firmware as a means of maintaining long-term access.
The exploitation of this vulnerability requires careful consideration of the underlying security architecture and the specific mechanisms by which SMM operates. The issue demonstrates the critical importance of firmware security and the need for proper input validation and privilege separation within system management mode components. Organizations should implement comprehensive firmware update strategies, including regular monitoring for firmware patches and updates from vendors. The vulnerability highlights the need for continuous security assessment of firmware components and the importance of maintaining current firmware versions. Security professionals should also consider implementing firmware integrity monitoring solutions that can detect unauthorized modifications to system firmware. From a compliance perspective, this vulnerability may impact various security standards including those related to firmware security, system integrity, and privileged access control. The affected systems require immediate attention through vendor-provided patches and firmware updates, while also implementing additional monitoring and detection measures to identify potential exploitation attempts. The vulnerability serves as a reminder of the critical nature of firmware security and the necessity for robust security controls at all layers of the system architecture.