CVE-2025-0677
MediumCVSS 6.4Exploitation Probability (EPSS)
Low risk24th percentile - higher than 24% of all known CVEs
Summary
A flaw was found in grub2's UFS module when handling symbolic links. The function checking symlink data size does not verify overflow, leading to undersized buffer allocation and heap out-of-bounds write. An attacker can craft a malicious filesystem to corrupt heap memory and achieve arbitrary code execution, bypassing Secure Boot.
Risk Assessment
The risk is bypassing Secure Boot and executing unauthorized code during system startup, potentially leading to full machine compromise and persistent boot integrity violation.
Recommendation
Immediately update GRUB2 to a patched version addressing CVE-2025-0677. Prior to update, restrict physical console access and verify GRUB image integrity.
Original NVD description (English source)
A flaw was found in grub2. When performing a symlink lookup, the grub's UFS module checks the inode's data size to allocate the internal buffer to read the file content, however, it fails to check if the symlink data size has overflown. When this occurs, grub_malloc() may be called with a smaller value than needed. When further reading the data from the disk into the buffer, the grub_ufs_lookup_symlink() function will write past the end of the allocated size. An attack can leverage this by crafting a malicious filesystem, and as a result, it will corrupt data stored in the heap, allowing for arbitrary code execution used to by-pass secure boot mechanisms.