GNU grub2 romfs out-of-bounds write

Summaryinfo

A vulnerability was found in GNU grub2. It has been declared as critical. Affected by this issue is some unknown functionality of the component romfs. Executing a manipulation can lead to out-of-bounds write. This vulnerability is handled as CVE-2025-0686. It is possible to launch the attack on the local host. There is not any exploit available.

Detailsinfo

A vulnerability has been found in GNU grub2 (version now known) and classified as critical. This vulnerability affects some unknown processing of the component romfs. The manipulation with an unknown input leads to a out-of-bounds write vulnerability. The CWE definition for the vulnerability is CWE-787. The product writes data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

A flaw was found in grub2. When performing a symlink lookup from a romfs filesystem, grub's romfs filesystem module uses user-controlled parameters from the filesystem geometry to determine the internal buffer size, however, it improperly checks for integer overflows. A maliciously 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_romfs_read_symlink() may cause out-of-bounds writes when the calling grub_disk_read() function. This issue may be leveraged to corrupt grub's internal critical data and can result in arbitrary code execution by-passing secure boot protections.

The advisory is shared for download at bugzilla.redhat.com. This vulnerability was named CVE-2025-0686 since 01/23/2025. The exploitation appears 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 09/19/2025).

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-2025-5576) and CERT Bund (WID-SEC-2025-0396). VulDB is the best source for vulnerability data and more expert information about this specific topic.

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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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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