🛡️ Sentinel: Fix exception detail leakage in login_required decorator

.jules/sentinel.md

@@ -0,0 +1,4 @@
+## 2025-02-23 - Prevent Exception Details Leakage in Auth Responses
+**Vulnerability:** `auth/utils.py`'s `@login_required` decorator exposed internal exception strings (`details: str(e)`) to clients upon authentication failure, risking exposure of database/cache state or internal implementation details.
+**Learning:** Returning `str(e)` in Flask error responses provides an easy path for information disclosure when third-party libraries or DB connections fail during auth verification.
+**Prevention:** Always log exception details internally via standard logging (`logger.warning` / `logger.error`) and return sanitized generic error responses (e.g. `{'error': 'Unauthorized'}`) to clients.

auth/utils.py

@@ -1,14 +1,17 @@
-import bcrypt
-import jwt
+import logging
 import os
 import secrets
 from datetime import datetime, timedelta
 from functools import wraps
+from typing import Tuple, Optional
+import bcrypt
+import jwt
 from flask import request, jsonify, g
 from flask_jwt_extended import get_jwt_identity, verify_jwt_in_request
 from cache_db.redis_client import redis_client
 from cache_db.models import User, RefreshToken
-from typing import Tuple, Optional
+
+logger = logging.getLogger(__name__)
 
 
 class PasswordUtils:
@@ -129,7 +132,9 @@ def decorated_function(*args, **kwargs):
             g.user = user_data
             return f(*args, **kwargs)
         except Exception as e:
-            return jsonify({'error': 'Unauthorized', 'details': str(e)}), 401
+            # SECURITY: Do not leak internal exception details to client
+            logger.warning("Authentication failed: %s", e)
+            return jsonify({'error': 'Unauthorized'}), 401
     return decorated_function
 
 

tests/test_auth_utils.py

@@ -0,0 +1,49 @@
+import sys
+from unittest.mock import MagicMock
+
+# Mock external cache_db module before importing auth.utils
+cache_db_mock = MagicMock()
+sys.modules['cache_db'] = cache_db_mock
+sys.modules['cache_db.redis_client'] = cache_db_mock
+sys.modules['cache_db.models'] = cache_db_mock
+
+from flask import Flask
+from auth.utils import PasswordUtils, JWTUtils, login_required
+
+
+def test_password_hashing():
+    pw = "secret_password123"
+    hashed = PasswordUtils.hash_password(pw)
+    assert PasswordUtils.verify_password(pw, hashed) is True
+    assert PasswordUtils.verify_password("wrong_password", hashed) is False
+
+
+def test_jwt_utils():
+    access, refresh = JWTUtils.create_tokens("u123", "alice")
+    decoded_access = JWTUtils.decode_token(access)
+    assert decoded_access["user_id"] == "u123"
+    assert decoded_access["username"] == "alice"
+    assert decoded_access["type"] == "access"
+
+
+def test_login_required_does_not_leak_details(monkeypatch):
+    app = Flask(__name__)
+
+    @app.route("/protected")
+    @login_required
+    def protected():
+        return "success", 200
+
+    def mock_verify():
+        raise RuntimeError("Sensitive DB exception with stack trace or internal connection details")
+
+    import flask_jwt_extended
+    monkeypatch.setattr(flask_jwt_extended, "verify_jwt_in_request", mock_verify)
+
+    client = app.test_client()
+    response = client.get("/protected")
+
+    assert response.status_code == 401
+    data = response.get_json()
+    assert data == {"error": "Unauthorized"}
+    assert "details" not in data