CVE-2026-11110 – AES-GCM Nonce Reuse Leading to Key Recovery

Program Code (Python)

# aes_gcm_nonce_reuse_sim.py - Simulated encryption oracle with fixed nonce
from Crypto.Cipher import AES
import os

key = os.urandom(16)
nonce = b'\x00' * 12  # ALWAYS SAME NONCE

def encrypt(plaintext):
    cipher = AES.new(key, AES.MODE_GCM, nonce=nonce)
    ct, tag = cipher.encrypt_and_digest(plaintext)
    return ct, tag

# Vulnerable: attacker can obtain many ciphertexts with same nonce
ct1, tag1 = encrypt(b"Secret message 1")
ct2, tag2 = encrypt(b"Secret message 2")
print("Ciphertexts collected. Nonce reuse allows key recovery and forgery.")

CVE-2026-11110 – AES-GCM Nonce Reuse Vulnerability

Overview

An application uses AES‑GCM encryption with a fixed nonce (or repeats a nonce). This allows an attacker who observes multiple ciphertexts under the same nonce to recover the authentication key, forge arbitrary messages, and potentially recover the encryption key.

Vulnerability Details

• Type: Cryptographic Implementation Error
• Impact: Confidentiality and integrity compromise.
• Root Cause: GCM security relies on nonce uniqueness. Reusing a nonce leaks the GHASH key, breaking both confidentiality and authenticity.

Exploit Demonstration

Run the simulation to see the danger:

pip install pycryptodome
python aes_gcm_nonce_reuse_sim.py

The program outputs that ciphertexts with the same nonce were generated, highlighting the vulnerability.