CVE-2020-27339 in InsydeH2O
Summary
by MITRE • 06/16/2021
In the kernel in Insyde InsydeH2O 5.x, certain SMM drivers did not correctly validate the CommBuffer and CommBufferSize parameters, allowing callers to corrupt either the firmware or the OS memory. The fixed versions for this issue in the AhciBusDxe, IdeBusDxe, NvmExpressDxe, SdHostDriverDxe, and SdMmcDeviceDxe drivers are 05.16.25, 05.26.25, 05.35.25, 05.43.25, and 05.51.25 (for Kernel 5.1 through 5.5).
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Analysis
by VulDB Data Team • 11/04/2025
This vulnerability exists within the InsydeH2O firmware implementation version 5.x where specific System Management Mode SMM drivers fail to properly validate memory parameters during firmware communication operations. The flaw affects critical drivers including AhciBusDxe, IdeBusDxe, NvmExpressDxe, SdHostDriverDxe, and SdMmcDeviceDxe which handle storage controller communications. The root cause lies in insufficient input validation of the CommBuffer and CommBufferSize parameters, creating a memory corruption vulnerability that can be exploited by unauthorized entities. This represents a classic buffer overflow condition where malicious actors can manipulate memory layout through improper parameter validation mechanisms. The vulnerability operates at the firmware level, specifically within the System Management Mode which has elevated privileges and direct access to system memory. This type of flaw falls under CWE-121 which describes stack-based buffer overflow conditions, though the specific context here involves firmware memory management rather than traditional software stack operations. The security implications are severe as this vulnerability allows for both firmware and operating system memory corruption, potentially enabling privilege escalation and persistent system compromise.
The operational impact of this vulnerability extends beyond simple memory corruption to encompass potential system instability and complete compromise of the firmware security model. Attackers can leverage this weakness to inject malicious code into firmware memory spaces, potentially creating backdoors that persist across system reboots and operating system installations. The affected drivers handle critical storage operations that are fundamental to system boot processes and data integrity, making this vulnerability particularly dangerous for enterprise and industrial environments. The vulnerability affects multiple kernel versions from 5.1 through 5.5, indicating a widespread issue across a significant portion of the firmware release cycle. This affects systems where InsydeH2O firmware is implemented, including but not limited to servers, embedded systems, and IoT devices that rely on this firmware for storage controller management. The exploitation of this vulnerability can lead to complete system compromise, data loss, and unauthorized access to sensitive system resources. The nature of SMM operations means that successful exploitation can bypass traditional operating system security controls and memory protection mechanisms.
Mitigation strategies for this vulnerability require immediate firmware updates to the specified versions or higher for each affected driver component. Organizations should prioritize updating systems running InsydeH2O firmware versions 5.x to ensure protection against this memory corruption vulnerability. The recommended fixed versions are 05.16.25 for AhciBusDxe, 05.26.25 for IdeBusDxe, 05.35.25 for NvmExpressDxe, 05.43.25 for SdHostDriverDxe, and 05.51.25 for SdMmcDeviceDxe. System administrators should conduct comprehensive inventory assessments to identify all affected systems and prioritize remediation efforts based on risk exposure. Additionally, implementing runtime monitoring and memory integrity checking mechanisms can help detect potential exploitation attempts. This vulnerability maps to ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and T1542 which addresses 'Pre-OS Boot' activities. Organizations should also consider implementing firmware integrity verification measures and maintaining detailed system baselines to detect unauthorized modifications. The vulnerability highlights the importance of secure firmware development practices and proper parameter validation in privileged execution environments. Regular firmware audits and vulnerability assessments should be conducted to identify similar issues in other firmware components and prevent similar security incidents from occurring in the future.