CVE-2025-0690 is a vulnerability identified in the GRUB bootloader, specifically related to the handling of keyboard input via the read command. The issue stems from the use of a 32-bit integer to track the length of user input during reads. When a sufficiently large input line is provided, this length variable can overflow, causing an out-of-bounds write in the heap-based buffer that stores the input line. This memory corruption can lead to the alteration of GRUB's internal critical data structures. Since GRUB is responsible for bootstrapping the operating system and enforcing secure boot policies, corruption here could allow an attacker to bypass secure boot protections, undermining system integrity from the earliest stage of the boot process. The vulnerability requires local privileged access (PR:H) and user interaction (UI:R), meaning an attacker must have some level of authenticated access and actively provide input to trigger the flaw. The CVSS v3.1 score is 6.1, reflecting medium severity with high impact on confidentiality, integrity, and availability if exploited. No public exploits are known at this time, and no patches or vendor advisories have been linked yet. The flaw was reserved in January 2025 and published in February 2025, indicating it is a recent discovery. Given GRUB's widespread use in Linux-based systems, especially in servers and embedded devices, this vulnerability poses a significant risk where secure boot is relied upon to prevent unauthorized code execution during system startup.

For European organizations, the impact of CVE-2025-0690 could be substantial, particularly in sectors relying heavily on Linux-based infrastructure with secure boot enabled, such as government agencies, critical infrastructure, cloud service providers, and large enterprises. Successful exploitation could allow attackers to bypass secure boot, enabling persistent rootkits or bootkits that evade detection by traditional security tools. This undermines system trustworthiness and could facilitate further compromise of sensitive data or critical services. The requirement for local privileged access and user interaction limits remote exploitation but does not eliminate risk from insider threats or attackers who gain initial footholds. The potential to corrupt bootloader data threatens system availability and integrity, possibly causing system failures or denial of service. Given the strategic importance of secure boot in maintaining supply chain and firmware security, this vulnerability could have cascading effects on compliance with European cybersecurity regulations such as NIS2 and GDPR if exploited.

To mitigate CVE-2025-0690, European organizations should implement several targeted measures beyond generic patching advice. First, restrict physical and local access to systems running vulnerable GRUB versions to trusted personnel only, reducing the risk of exploitation requiring user interaction. Employ strong access controls and monitoring to detect unauthorized local access attempts. Implement bootloader integrity verification mechanisms, such as TPM-based measurements and remote attestation, to detect unauthorized modifications to GRUB. Organizations should prioritize deploying vendor patches or updates as soon as they become available, and in the interim, consider disabling or limiting interactive input at the bootloader stage if feasible. Regularly audit and update secure boot configurations to ensure they are correctly enforced. Additionally, conduct security awareness training to inform administrators about the risks of local privilege escalation and secure boot bypass attacks. For critical systems, consider deploying intrusion detection systems that monitor boot process anomalies. Finally, maintain up-to-date backups and recovery plans to restore systems in case of compromise.