Program Code (Python with ldap3 simulation)

# ldap_server_sim.py - Simulated LDAP authentication server
from flask import Flask, request, jsonify

app = Flask(__name__)

# Fake user database
USERS = {
    'admin': {'password': 'secret', 'role': 'admin'},
    'user': {'password': 'pass', 'role': 'user'}
}

def ldap_search(username, password):
    # Simulate an LDAP filter injection: user-controlled username goes directly into filter
    # Real LDAP query: (&(uid={username})(userPassword={password}))
    # Here we just simulate: if the username contains wildcard, it may bypass.
    if '*' in username:
        # Vulnerability: filter becomes (uid=*) which matches any user
        # We'll return the first matching user (admin)
        return USERS.get('admin')
    return USERS.get(username)

@app.route('/login', methods=['POST'])
def login():
    username = request.form.get('username')
    password = request.form.get('password')
    user = ldap_search(username, password)
    if user and user['password'] == password:
        return jsonify({"message": "Authenticated", "role": user['role']})
    return jsonify({"message": "Invalid"}), 401

if __name__ == '__main__':
    app.run(port=5000)

Overview

An authentication system constructs an LDAP search filter by directly concatenating user input without escaping special characters. An attacker can inject wildcards (*) to bypass authentication or enumerate users.

Vulnerability Details

Type: LDAP Injection
Impact: Authentication bypass, information disclosure.
Root Cause: The username parameter is not sanitised, allowing characters like *, (, ) to modify the LDAP filter logic.

Exploit Demonstration

Start the simulated vulnerable server:
```
pip install flask
python ldap_server_sim.py
```
Run the exploit:
```
python exploit_ldap_injection.py
```

CVE-2026-5050-Blind-LDAP-Injection-via-Unescaped-Filter

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