CVE-2025-0685 Grub2: jfs: integer overflow when handling symlinks may lead to heap based out-of-bounds write when reading data

Description

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.

Exploitable with local access to the machine, with an administrator account and without any user action; an attacker can seriously compromise confidentiality, integrity or availability.

Attack vector

Local

Attack complexity

High

Privileges required

High

Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Affected products and versions