CVE-2022-32266 is a vulnerability identified in InsydeH2O firmware versions with kernel versions 5.0 through 5.5, excluding 5.2. The issue arises from a Time-of-Check to Time-of-Use (TOCTOU) race condition in the handling of the parameter buffer by a software System Management Interrupt (SMI) handler, specifically the PcdSmmDxe driver. The vulnerability allows Direct Memory Access (DMA) attacks on the parameter buffer, which can lead to corruption of other Advanced Configuration and Power Interface (ACPI) fields and adjacent memory regions. Exploiting this vulnerability requires detailed knowledge of the Platform Configuration Database (PCD) contents specific to the platform, indicating that the attacker must have significant insight into the firmware internals. The flaw is categorized under CWE-787 (Out-of-bounds Write), highlighting that the memory corruption stems from improper handling of buffer boundaries during the race condition. The vulnerability affects the firmware's kernel versions 5.0 through 5.5 (except 5.2), with fixes released in versions 05.36.23 (kernel 5.3), 05.44.23 (kernel 5.4), and 05.52.23 (kernel 5.5). The CVSS v3.1 base score is 6.4, indicating a medium severity level, with an attack vector of local (AV:L), high attack complexity (AC:H), requiring high privileges (PR:H), no user interaction (UI:N), unchanged scope (S:U), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). No known exploits are currently reported in the wild. This vulnerability is significant because the SMI handler operates at a high privilege level within the System Management Mode (SMM), which is a highly privileged execution environment isolated from the operating system. Successful exploitation could allow an attacker with local high privileges and DMA capabilities to corrupt critical firmware data structures, potentially leading to system instability, privilege escalation, or persistent firmware compromise.

For European organizations, the impact of CVE-2022-32266 can be substantial, particularly in sectors relying heavily on hardware-level security and firmware integrity, such as finance, telecommunications, critical infrastructure, and government agencies. The vulnerability enables an attacker with local high privileges and DMA access to corrupt ACPI and adjacent memory fields, potentially leading to system crashes, data corruption, or unauthorized firmware modifications. This could undermine system integrity and availability, disrupt business operations, and facilitate persistent attacks that bypass traditional OS-level security controls. Given that the vulnerability affects InsydeH2O firmware—a widely used BIOS/UEFI firmware in many laptop and embedded device manufacturers—organizations using affected hardware may face increased risk of targeted attacks, especially in environments where physical or local access is possible. The requirement for detailed platform-specific knowledge and high privileges limits the attack surface but does not eliminate risk in scenarios involving insider threats, compromised administrative accounts, or sophisticated attackers with physical access. The absence of known exploits in the wild currently reduces immediate risk, but the medium severity and potential for high-impact outcomes necessitate proactive mitigation to prevent exploitation.

1. Firmware Updates: Immediately verify the firmware versions of devices using InsydeH2O and apply the vendor-provided patches that address this vulnerability (kernel versions 5.3, 5.4, 5.5 with respective fixed firmware versions 05.36.23, 05.44.23, 05.52.23). Coordinate with hardware vendors to ensure timely deployment of updates. 2. Restrict DMA Access: Implement hardware and software controls to restrict DMA access to trusted devices only. Utilize Input-Output Memory Management Units (IOMMUs) to limit DMA capabilities and prevent unauthorized memory access. 3. Limit Privileged Access: Enforce strict access controls to limit users with high privileges capable of triggering SMI handlers. Use role-based access control (RBAC) and monitor privileged account activities to detect anomalies. 4. Physical Security: Enhance physical security measures to prevent unauthorized local access to devices, as exploitation requires local presence and detailed platform knowledge. 5. Firmware Integrity Monitoring: Deploy firmware integrity verification tools to detect unauthorized modifications or corruption in ACPI tables and firmware memory regions. 6. Incident Response Preparedness: Develop and test incident response plans specific to firmware-level compromises, including forensic capabilities to analyze SMM and ACPI-related anomalies. 7. Vendor Coordination: Engage with hardware and firmware vendors to receive timely security advisories and participate in coordinated vulnerability disclosure programs to stay ahead of emerging threats.