CVE-2025-0690: Integer Overflow Vulnerability in GRUB2

🛡️ Overview

CVE-2025-0690 is a critical integer overflow vulnerability in the GRUB2 boot loader, allowing arbitrary code execution and Secure Boot bypass. This flaw affects systems that rely on GRUB2 for secure boot, exposing the system before the operating system starts.

🔍 Technical Details

Root Cause

• Vulnerable command: read (used to receive keyboard input).
• Issue: Input length is stored in a 32-bit integer.
• Exploitation Mechanism:
  • Enter an extremely long line of text.
  • Causes an overflow in the length variable.
  • This leads to an out-of-bounds write in a heap-based buffer.

Consequences

• Corruption of critical internal data of GRUB2.
• Secure Boot bypass, allowing loading of malicious kernels.
• System compromise before the OS starts.

📊 Security Metrics (CVSS v3.1)

🛠️ Solutions and Mitigation

Available Updates

Several vendors have released patches to fix this vulnerability:

Recommendations

1. Update GRUB2 and dependencies:
   • Use your distribution's package manager:
     root@kitploit:~

     sudo dnf update grub2 grub2-common grub2-efi  # RHEL/Fedora
     sudo apt upgrade grub2 grub2-common grub2-efi # Debian/Ubuntu
     

2. Verify the installed version:
   root@kitploit:~

   grub-install --version
   

3. Reboot the system after the update.

📌 Additional Notes

• CWE-787: Vulnerability classification as out-of-bounds write.
• Publication Date: 24/02/2025.
• Last Modification: 15/04/2026.

🔗 Official References

• Red Hat Security Advisory (RHSA-2025:6990)
• CVE-2025-0690 at Red Hat
• Red Hat Bugzilla #2346123
• GRUB2 Mailing List

Kaleth Pwned!!