CVE-2025-0677: Grub2: ufs: integer overflow may lead to heap based out-of-bounds write when handling symlinks

Severity: medium (CVSS 6.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-02-19 · updated 2026-10-21
Weakness: CWE-787

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.

Affected products

Red Hat OpenShift Container Platform 4.18: all versions
Red Hat Enterprise Linux 10: all versions — fixed in 1:2.12-15.el10_0
Red Hat Enterprise Linux 9: all versions — fixed in 1:2.06-104.el9_6

How to fix

Upgrade to a fixed version: Red Hat Enterprise Linux 10 1:2.12-15.el10_0; Red Hat Enterprise Linux 9 1:2.06-104.el9_6. Check the vendor advisory for mitigations.

References

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