CVE-2025-61663
📋 TL;DR
A use-after-free vulnerability in GRUB2's normal command allows attackers to cause denial of service by accessing invalid memory when the module is unloaded. This affects systems using vulnerable GRUB2 versions, potentially leading to system crashes. The vulnerability requires local access to execute the normal command.
💻 Affected Systems
- GRUB2
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete system crash requiring physical intervention to reboot, potentially corrupting boot configuration and requiring recovery media.
Likely Case
System instability leading to crashes during boot or when GRUB2 modules are manipulated, requiring manual reboot.
If Mitigated
Limited impact with proper access controls preventing unauthorized users from executing GRUB2 commands.
🎯 Exploit Status
Exploitation requires local access to execute the normal command during boot process or through GRUB2 shell.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check vendor-specific updates (e.g., Red Hat, Ubuntu, Debian security advisories)
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2025-61663
Restart Required: Yes
Instructions:
1. Check your distribution's security advisory for GRUB2 updates. 2. Apply the security update via package manager (e.g., 'yum update grub2' or 'apt upgrade grub2'). 3. Reboot the system to load the patched GRUB2.
🔧 Temporary Workarounds
Restrict physical and console access
linuxPrevent unauthorized users from accessing system console or boot environment where GRUB2 commands can be executed.
Configure GRUB2 password protection
linuxSet a GRUB2 password to prevent unauthorized command execution during boot.
grub2-mkpasswd-pbkdf2
Add 'set superusers="username"' and 'password_pbkdf2 username hashed_password' to /etc/grub.d/40_custom
grub2-mkconfig -o /boot/grub2/grub.cfg
🧯 If You Can't Patch
- Implement strict physical security controls to prevent unauthorized console access.
- Monitor for unauthorized GRUB2 configuration changes and boot environment access attempts.
🔍 How to Verify
Check if Vulnerable:
Check GRUB2 version: 'grub2-install --version' or 'rpm -q grub2' / 'dpkg -l grub2'. Compare against vendor security advisories.Check Version:
grub2-install --versionVerify Fix Applied:
Verify updated GRUB2 package is installed: 'rpm -q grub2 --changelog | grep CVE-2025-61663' or check package version matches patched release.📡 Detection & Monitoring
Log Indicators:
- Unexpected system crashes during boot
- GRUB2 error messages in kernel logs
- Console access logs showing unauthorized boot menu interactions
Network Indicators:
- Not network exploitable - local access required
SIEM Query:
Search for: 'GRUB2 crash', 'kernel panic during boot', 'console access outside maintenance windows'