CVE-2025-0677: grub2 Out-of-bounds Write

Vulnerability summary

CVE-2025-0677 is a medium (CVSS 6.4) Out-of-bounds Write vulnerability in grub2. EPSS estimates a 0.33% chance of exploitation in the next 30 days, higher than 24.3% of scored vulnerabilities.

Timeline

1. 19-02-2025
   PublishedVulnerability first disclosed.
2. 29-06-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.