Buffer overflow in GNU Grub2
CVE-2025-0686
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.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.4 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.003 (18.1th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 18th percentile — 18.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- access.redhat.com/security/cve/CVE-2025-0686 (vdb-entry, Vendor Advisory)
- bugzilla.redhat.com/show_bug.cgi (issue-tracking, Issue Tracking)
- lists.gnu.org/archive/html/grub-devel/2025-02/msg00024.html
Frequently asked questions
- What is CVE-2025-0686?
- CVE-2025-0686 is a medium-severity vulnerability in GNU Grub2, classified under Out-of-bounds Write. CVSS score: 6.4/10. Published 2025-03-03.
- How severe is CVE-2025-0686?
- Medium severity. CVSS v3 base score is 6.4 out of 10.
- Is CVE-2025-0686 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.