CVE-2025-61661
📋 TL;DR
A vulnerability in GRUB bootloader allows local attackers to cause denial of service by connecting malicious USB devices during boot. The flaw involves improper string conversion when reading USB device information, which can crash GRUB and potentially corrupt data. Systems using GRUB with USB boot capability are affected.
💻 Affected Systems
- GRUB (Grand Unified Bootloader)
⚠️ 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
Permanent boot failure requiring physical recovery, potential data corruption on boot devices
Likely Case
Temporary boot failure requiring manual reboot, no data loss
If Mitigated
No impact if USB boot is disabled or physical access controls prevent malicious USB connections
🎯 Exploit Status
Requires physical access during boot sequence and specially crafted USB device
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check vendor-specific updates (e.g., Red Hat, Ubuntu, etc.)
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2025-61661
Restart Required: Yes
Instructions:
1. Check for GRUB updates from your distribution vendor. 2. Apply security updates via package manager. 3. Reboot system to load patched GRUB.
🔧 Temporary Workarounds
Disable USB boot
linuxPrevent GRUB from booting from USB devices
Edit /etc/default/grub and add 'GRUB_DISABLE_USB=1'
Run 'update-grub' (or grub2-mkconfig on RHEL)
BIOS/UEFI USB boot disable
allDisable USB boot at firmware level
🧯 If You Can't Patch
- Implement physical security controls to prevent unauthorized USB device connections
- Disable USB ports in BIOS/UEFI settings where possible
🔍 How to Verify
Check if Vulnerable:
Check GRUB version and compare with vendor patched versionsCheck Version:
grub-install --version or rpm -q grub2 (RHEL) or dpkg -l grub* (Debian/Ubuntu)Verify Fix Applied:
Verify GRUB package version matches vendor's patched version📡 Detection & Monitoring
Log Indicators:
- GRUB boot failures
- Kernel panic during boot
- USB device connection errors in boot logs
Network Indicators:
- None - local physical attack only
SIEM Query:
Search for boot failure events or GRUB error messages in system logs