CVE-2025-1125 – This vulnerability in GRUB's HFS filesystem mod... (How to Fix)

Q: What is the severity of CVE-2025-1125?

CVE-2025-1125 has a CVSS score of 7.8 (HIGH). This vulnerability in GRUB's HFS filesystem module allows integer overflow when calculating buffer sizes from malicious filesystem metadata. Attackers can exploit this to write past allocated buffers, potentially executing arbitrary code and bypassing Secure Boot protections. Systems using GRUB with HFS/HFS+ filesystem support are affected.

📋 TL;DR

This vulnerability in GRUB's HFS filesystem module allows integer overflow when calculating buffer sizes from malicious filesystem metadata. Attackers can exploit this to write past allocated buffers, potentially executing arbitrary code and bypassing Secure Boot protections. Systems using GRUB with HFS/HFS+ filesystem support are affected.

💻 Affected Systems

Products:

GRUB2

Versions: All versions before the fix

Operating Systems: Linux distributions using GRUB2, Any OS using GRUB2 bootloader

Default Config Vulnerable: ⚠️ Yes

Notes: Only exploitable when GRUB processes HFS/HFS+ filesystems during boot, which is uncommon in typical Linux installations.

📦 What is this software?

Grub2 by Gnu

View all CVEs affecting Grub2 →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system compromise via arbitrary code execution during boot process, bypassing Secure Boot and gaining persistent access to the system.

🟠

Likely Case

System instability or crash during boot when processing malicious HFS filesystems, potentially leading to denial of service.

🟢

If Mitigated

Limited impact if systems don't mount HFS filesystems during boot and have Secure Boot enabled with proper certificate management.

🌐 Internet-Facing: LOW

🏢 Internal Only: MEDIUM

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: HIGH

Exploitation requires physical access or ability to modify boot media/filesystems, and precise control over HFS metadata.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Check vendor-specific patches (e.g., Red Hat, Ubuntu, Debian)

Vendor Advisory: https://access.redhat.com/security/cve/CVE-2025-1125

Restart Required: Yes

Instructions:

1. Check your distribution's security advisories. 2. Update GRUB2 package via package manager. 3. Regenerate GRUB configuration. 4. Reboot system.

🔧 Temporary Workarounds

Disable HFS module

linux

Remove or disable GRUB's HFS filesystem module to prevent processing of HFS filesystems

# Remove hfs module from GRUB configuration
# Edit /etc/default/grub or grub.cfg

Secure Boot enforcement

all

Ensure Secure Boot is properly configured and enabled to prevent unauthorized boot code execution

🧯 If You Can't Patch

Restrict physical access to systems and boot media
Implement strict controls on boot media and filesystem sources

🔍 How to Verify

Check if Vulnerable:

Check GRUB version and verify if HFS module is present: grub-install --version

Check Version:

grub-install --version

Verify Fix Applied:

Verify GRUB package version matches patched version from vendor advisory

📡 Detection & Monitoring

Log Indicators:

GRUB boot errors related to HFS filesystems
System crashes during boot process

Network Indicators:

None - local exploitation only

SIEM Query:

Search for: 'grub' AND ('hfs' OR 'boot error' OR 'kernel panic') in system logs

📊 Metadata

CVE ID: CVE-2025-1125

CVSS v3 Score: 7.8 (HIGH)

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

CWE: CWE-787

EPSS Score: 0.03% exploit probability (8.2th percentile)

Published: March 3, 2025

Last Updated: January 8, 2026

🔗 References

https://access.redhat.com/security/cve/CVE-2025-1125 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2346138 Issue Tracking,Third Party Advisory
https://lists.gnu.org/archive/html/grub-devel/2025-02/msg00024.html Mailing List,Vendor Advisory

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🔗 Related Vulnerabilities

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