CVE-2025-0685
MediumCVSS 6.4Exploitation Probability (EPSS)
Low risk16th percentile - higher than 16% of all known CVEs
Summary
A buffer overflow vulnerability was found in the jfs filesystem module of GRUB2. The grub_jfs_lookup_symlink() function writes beyond the allocated buffer when a specially crafted jfs filesystem is used. This can corrupt critical internal GRUB data and potentially lead to arbitrary code execution.
Risk Assessment
An attacker with physical access or the ability to mount a malicious jfs filesystem can bypass Secure Boot protections and gain unauthorized code execution during system startup. This poses a serious threat to the boot process integrity.
Recommendation
Immediately update GRUB2 to a version containing the fix for CVE-2025-0685. If an update is not possible, consider temporarily disabling jfs filesystem support in the GRUB configuration.
Original NVD description (English source)
A flaw was found in grub2. When reading data from a jfs filesystem, grub's jfs filesystem module uses user-controlled parameters from the filesystem geometry to determine the internal buffer size, however, it improperly checks for integer overflows. A maliciouly crafted filesystem may lead some of those buffer size calculations to overflow, causing it to perform a grub_malloc() operation with a smaller size than expected. As a result, the grub_jfs_lookup_symlink() function will write past the internal buffer length during grub_jfs_read_file(). This issue can be leveraged to corrupt grub's internal critical data and may result in arbitrary code execution, by-passing secure boot protections.