CVE-2025-0624 is a vulnerability identified in grub2, the widely used bootloader in many Linux-based systems. The flaw occurs during the network boot process, specifically when grub attempts to locate and load its configuration file. grub copies data from a user-controlled environment variable into an internal buffer using the grub_strcpy() function. However, grub fails to properly consider the length of this environment variable when allocating memory for the buffer, resulting in an out-of-bounds write. This memory corruption can be exploited by an attacker positioned on the same network segment to execute arbitrary code remotely during the boot process. Such exploitation can bypass secure boot protections, which are designed to ensure that only trusted software is loaded during system startup. The vulnerability requires the attacker to have high privileges on the network (e.g., access to the local network segment) but does not require user interaction. The CVSS v3.1 score is 7.6, reflecting high impact on confidentiality, integrity, and availability, with attack vector being adjacent network and requiring high privileges. No public exploits are known at this time, but the potential for remote code execution during boot makes this a critical concern for environments relying on network booting with grub2. The vulnerability affects all versions of grub2 that perform network booting and handle environment variables in this manner. Because grub2 is commonly used in Linux servers and embedded systems, this vulnerability could have broad implications.

For European organizations, the impact of CVE-2025-0624 can be significant, particularly for those that utilize network booting (PXE boot) in their infrastructure. This includes data centers, cloud providers, and enterprises with large-scale Linux server deployments. Successful exploitation could allow attackers to execute arbitrary code at boot time, effectively gaining control over affected systems before the operating system loads. This undermines secure boot mechanisms, potentially allowing persistent, stealthy malware installation that is difficult to detect or remove. Confidentiality of sensitive data could be compromised, integrity of systems corrupted, and availability disrupted through system crashes or malicious payloads. Critical infrastructure sectors such as finance, telecommunications, and government agencies in Europe that rely on secure and trusted boot processes are particularly at risk. The requirement for network adjacency limits remote exploitation but does not eliminate risk in shared or poorly segmented networks. The absence of known exploits currently provides a window for mitigation, but the high severity score indicates urgent attention is needed.

1. Apply official patches from grub2 maintainers or Linux distribution vendors as soon as they become available to address the out-of-bounds write issue. 2. Restrict network boot capabilities to trusted network segments and devices only, using VLANs or network access controls to limit exposure. 3. Implement strict network segmentation to isolate boot servers and PXE infrastructure from general user networks. 4. Monitor network traffic on boot-related protocols (e.g., DHCP, TFTP) for anomalous or unexpected activity that could indicate exploitation attempts. 5. Disable network boot on systems where it is not required to reduce the attack surface. 6. Use hardware-based secure boot features in conjunction with software protections to provide layered defense. 7. Conduct regular audits of boot configurations and environment variables to ensure no unauthorized changes. 8. Educate system administrators about the risks of network boot vulnerabilities and the importance of patch management. 9. Employ intrusion detection systems capable of recognizing exploitation patterns targeting boot processes. 10. Maintain up-to-date backups and recovery plans to mitigate impact in case of successful exploitation.