CVE-2025-0686: gnu grub2 Out-of-bounds Write
Vulnerability summary
CVE-2025-0686 is a medium (CVSS 6.4) Out-of-bounds Write vulnerability in gnu grub2. EPSS estimates a 0.28% chance of exploitation in the next 30 days, higher than 18.8% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 9 · Related 9Timeline
- 03-03-2025PublishedVulnerability first disclosed.
- 29-06-2026Last modifiedVulnerability information updated.
Description
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.
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated6.4MediumCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated6.4MediumCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
- NVDNIST6.4MediumCVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
0.28%
Chance of exploitation in the next 30 days
Percentile
19%
Versus all other CVEs
30-day change
0.00 pp
From 0.28% on 18-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu3 products
- grub2All versions (No fix recorded)
- grub2-signedAll versions (No fix recorded)
- grub2-unsignedAll versions (No fix recorded)
Debian1 product
- grub2< 2.06-13+deb12u2 | < 2.12-6
Gnu1 product
- grub2≤ 2.12
3 vendors · 5 products
