CVE-2025-0677 is a vulnerability in the GRUB2 bootloader, specifically within its UFS filesystem module. The flaw arises during symbolic link (symlink) resolution when the module attempts to allocate a buffer based on the inode's data size. However, it fails to verify whether the symlink data size has overflowed, causing grub_malloc() to allocate a buffer smaller than necessary. Subsequent reads from disk into this undersized buffer result in an out-of-bounds write, corrupting heap memory. This heap corruption can be exploited by an attacker who crafts a malicious filesystem containing specially designed symlinks. The consequence is the potential for arbitrary code execution within the bootloader context, which is particularly dangerous as it can be used to bypass secure boot mechanisms that protect system integrity during startup. The vulnerability requires local access with high privileges (as indicated by CVSS vector AV:L/PR:H) and does not require user interaction. The CVSS score of 6.4 reflects the moderate complexity of exploitation and the significant impact on confidentiality, integrity, and availability. No public exploits are known at this time, but the risk remains due to the critical role of GRUB2 in system boot processes.

For European organizations, the impact of CVE-2025-0677 can be substantial, especially for entities relying on Linux systems with GRUB2 bootloaders that support UFS filesystems. Successful exploitation could allow attackers to execute arbitrary code early in the boot process, effectively bypassing secure boot protections and compromising the system's trust chain. This can lead to persistent malware infections, unauthorized access to sensitive data, and disruption of critical services. Sectors such as finance, government, energy, and telecommunications, which often enforce secure boot policies to maintain system integrity, are particularly at risk. Additionally, organizations using virtualized environments or cloud services that employ GRUB2 may face indirect exposure if underlying infrastructure is vulnerable. The requirement for local high-privilege access limits remote exploitation but does not eliminate risk from insider threats or attackers who gain initial footholds through other means.

Organizations should monitor vendor advisories closely and apply patches or updates to GRUB2 as soon as they become available. In the interim, restricting local administrative access and enforcing strict privilege separation can reduce the risk of exploitation. System administrators should audit systems to identify those using GRUB2 with UFS support and consider disabling UFS support if not required. Implementing robust filesystem integrity checks and monitoring for unusual bootloader behavior can help detect exploitation attempts. Additionally, reinforcing secure boot configurations and ensuring firmware and bootloader components are up to date will strengthen defenses. For environments where patching is delayed, consider deploying host-based intrusion detection systems (HIDS) to monitor for anomalous activities indicative of heap corruption or bootloader tampering.