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Grub2Application · Gnu

CVE-2025-0685

MEDIUM · 6.4 CVSS v3.1 Published 2025-03-03
Fix available
A fix is available. Upgrade to after 2.12 or later.
See remediation →
66/100
Remediation priority · Elevated
Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A flaw was found in grub2. When reading data from a jfs filesystem, grub's jfs filesystem module uses user-controlled parameters from the filesystem geometry to determine the internal buffer size, however, it improperly checks for integer overflows. A maliciouly 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_jfs_lookup_symlink() function will write past the internal buffer length during grub_jfs_read_file(). This issue can be leveraged to corrupt grub's internal critical data and may result in arbitrary code execution, by-passing secure boot protections.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A flaw in grub2's jfs filesystem module allows integer overflow when calculating buffer sizes from user-controlled filesystem geometry parameters. A maliciously crafted jfs filesystem causes grub_malloc() to allocate a smaller buffer than required, leading to buffer overflow in grub_jfs_lookup_symlink() during grub_jfs_read_file(), corrupting internal data and potentially enabling arbitrary code execution to bypass Secure Boot.

MitigationUpdate grub2 to a version with integer overflow validation in the jfs filesystem module's buffer size calculations, and re-validate Secure Boot signatures after applying the update.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Grub2Application
Affected:<= 2.12

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
High
Privileges
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify installed Grub2 version
    Run 'grub2-install --version' or 'grub-install --version' to get the installed Grub2 version number
    Affected if The version is 2.12 or lower (any version <= 2.12)
  2. Locate the jfs filesystem module
    Search for the jfs module file (jfs.mod) in typical Grub2 module directories such as /usr/lib/grub/*/jfs.mod or /boot/grub/*/jfs.mod
    Affected if The jfs.mod file exists in the Grub2 module directory, indicating jfs support is available
  3. Check if jfs is compiled into the Grub2 image
    Inspect the Grub2 core image (usually /boot/grub/i386-pc/normal.mod or the equivalent for the system architecture) using 'modinfo' or by checking the Grub configuration for 'jfs' references in the module list
    Affected if jfs support is compiled into Grub or listed as available modules
  4. Verify if system uses or mounts jfs filesystems
    Check /etc/fstab for jfs filesystem entries, run 'mount | grep jfs', or examine any custom grub.cfg for jfs-related menu entries
    Affected if The system has jfs filesystems configured or the grub environment loads jfs module

A system is affected if it runs Grub2 version 2.12 or lower AND has the jfs filesystem module available or enabled, since the integer overflow vulnerability can be triggered by mounting a malicious jfs filesystem.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 2.12
Interim mitigation

Update grub2 to a version with integer overflow validation in the jfs filesystem module's buffer size calculations, and re-validate Secure Boot signatures after applying the update.

Recommended fix Moderate confidence

Grub2 version greater than 2.12 (e.g., 2.12 or later with the CVE-2025-0685 fix - check distribution-specific security advisories for the exact fixed version)

  1. Check the current installed version of grub2 on the system using 'grub2-install --version' or checking the package manager (e.g., 'rpm -q grub2' or 'dpkg -l grub2')
  2. Verify the system uses JFS filesystem on any boot-critical partitions by checking /etc/fstab or using 'lsblk -f'
  3. Update the system package repository to ensure latest packages are available
  4. Apply the grub2 update via the appropriate package manager (e.g., 'dnf update grub2' or 'apt-get install grub2')
  5. After updating grub2 packages, regenerate grub configuration if necessary using 'grub2-mkconfig -o /boot/grub2/grub.cfg' (or the appropriate path for the system)
  6. Reboot the system to load the updated grub2 and verify the system boots successfully
Caveat Minor risk: grub configuration changes may be needed if custom module configurations exist; ensure backups of current grub config exist before update

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Grub2 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA6.0 h
30.0 hours of engineering $5,120
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-0685 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data