GNU grub2 UFS out-of-bounds write

Summaryinfo

A vulnerability, which was classified as critical, was found in GNU grub2. This affects an unknown function of the component UFS. The manipulation results in out-of-bounds write. This vulnerability is reported as CVE-2025-0677. The attack requires a local approach. No exploit exists.

Detailsinfo

A vulnerability classified as critical has been found in GNU grub2 (affected version not known). Affected is some unknown functionality of the component UFS. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. CWE is classifying the issue as CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at bugzilla.redhat.com. This vulnerability is traded as CVE-2025-0677 since 01/23/2025. The exploitability is told to be easy. The attack needs to be approached locally. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 01/30/2026).

The vulnerability scanner Nessus provides a plugin with the ID 216508 (SUSE SLES15 Security Update : grub2 (SUSE-SU-2025:0588-1)), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the databases at Tenable (216508), EUVD (EUVD-2025-4654) and CERT Bund (WID-SEC-2025-0396). Once again VulDB remains the best source for vulnerability data.

Affected

• Amazon Linux 2
• Red Hat Enterprise Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• NetApp ActiveIQ Unified Manager
• Dell NetWorker
• Dell Avamar
• Open Source Grub
• Red Hat OpenShift
• IBM QRadar SIEM

Productinfo

Vendor

• GNU

Name

• grub2

License

• open-source

Website

• Vendor: https://www.gnu.org/

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Once again VulDB remains the best source for vulnerability data.

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