CVE-2025-61663 is a Use-after-Free vulnerability identified in the GNU GRUB2 bootloader, specifically within the normal command functionality. The vulnerability occurs because the normal command is not properly unregistered when its associated module is unloaded, leaving dangling pointers that reference freed memory. An attacker able to execute the normal command can cause the system to dereference these expired pointers, leading to memory corruption and system instability. This results in a Denial of Service (DoS) condition where the system may crash or halt, impacting availability. Although the primary consequence is DoS, the vulnerability also poses potential risks to data confidentiality and integrity due to memory corruption, though these impacts are less certain. The flaw requires local access to execute the normal command, has high attack complexity, and does not require privileges or user interaction. The vulnerability affects all versions of GRUB2, a widely used bootloader in Linux-based systems. No patches or known exploits are currently available, and no exploits have been observed in the wild. The CVSS v3.1 score is 4.9, reflecting medium severity with low confidentiality, integrity, and availability impacts, but high attack complexity and local attack vector.

For European organizations, the primary impact of CVE-2025-61663 is the risk of Denial of Service on systems using the GRUB2 bootloader, which is prevalent in Linux environments across enterprises, government, and critical infrastructure sectors. A successful exploit could cause system crashes during boot or normal operation, leading to downtime and potential disruption of services. This is particularly critical for servers, industrial control systems, and other infrastructure where uptime is essential. Although the vulnerability requires local access, insider threats or attackers who gain initial foothold could leverage this to disrupt operations. Potential impacts on data confidentiality and integrity, while not confirmed, raise concerns for sensitive environments handling critical or regulated data. The lack of known exploits reduces immediate risk, but the widespread use of GRUB2 means that unpatched systems remain vulnerable to future exploitation. Organizations in sectors such as finance, healthcare, energy, and government in Europe could face operational and reputational damage if affected.

1. Monitor for official patches or updates from GNU and Linux distribution vendors and apply them promptly once available. 2. Restrict local access to systems running GRUB2 to trusted personnel only, employing strict access controls and monitoring for unauthorized command execution. 3. Implement system integrity monitoring to detect abnormal behavior or crashes related to bootloader operations. 4. Use secure boot mechanisms and firmware protections to limit unauthorized modifications to bootloader components. 5. Employ multi-factor authentication and robust endpoint security to reduce the risk of attackers gaining local access. 6. Regularly audit and harden bootloader configurations to minimize exposure to exploitation. 7. For critical systems, consider redundancy and failover strategies to mitigate potential downtime from DoS conditions. 8. Educate system administrators about this vulnerability and the importance of controlling access to bootloader commands.