diff --git a/auth/utils.py b/auth/utils.py
index 4bded89..6a2ea13 100644
--- a/auth/utils.py
+++ b/auth/utils.py
@@ -1,14 +1,18 @@
-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 +133,8 @@ 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
+            logger.exception("Unauthorized access attempt: %s", e)
+            return jsonify({'error': 'Unauthorized'}), 401
     return decorated_function
 
 
diff --git a/tests/test_auth.py b/tests/test_auth.py
new file mode 100644
index 0000000..acaae91
--- /dev/null
+++ b/tests/test_auth.py
@@ -0,0 +1,69 @@
+"""
+Unit tests for auth/utils.py security fixes and utilities.
+"""
+
+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.redis_client
+sys.modules['cache_db.models'] = cache_db_mock.models
+
+import pytest
+from flask import Flask, jsonify
+from auth.utils import PasswordUtils, JWTUtils, login_required
+
+
+@pytest.fixture
+def app():
+    """Create a test Flask application."""
+    app = Flask(__name__)
+    app.config['SECRET_KEY'] = 'test-secret-key'
+    app.config['JWT_SECRET_KEY'] = 'test-jwt-secret-key'
+
+    @app.route('/protected')
+    @login_required
+    def protected():
+        return jsonify({'message': 'success'})
+
+    return app
+
+
+def test_password_hashing():
+    """Test password hashing and verification."""
+    password = "SuperSecretPassword123!"
+    hashed = PasswordUtils.hash_password(password)
+    assert hashed != password
+    assert PasswordUtils.verify_password(password, hashed) is True
+    assert PasswordUtils.verify_password("WrongPassword", hashed) is False
+
+
+def test_password_length_validation():
+    """Test password length requirement."""
+    with pytest.raises(ValueError, match="at least 8 characters"):
+        PasswordUtils.hash_password("short")
+
+
+def test_jwt_token_creation_and_decoding():
+    """Test JWT token creation and decoding."""
+    access_token, refresh_token = JWTUtils.create_tokens("user123", "testuser")
+    assert access_token is not None
+    assert refresh_token is not None
+
+    decoded_access = JWTUtils.decode_token(access_token)
+    assert decoded_access is not None
+    assert decoded_access["user_id"] == "user123"
+    assert decoded_access["username"] == "testuser"
+    assert decoded_access["type"] == "access"
+
+
+def test_login_required_unauthorized_no_leak(app):
+    """Test that login_required returns 401 and does NOT leak internal exception details."""
+    with app.test_client() as client:
+        response = client.get('/protected')
+        assert response.status_code == 401
+        data = response.get_json()
+        assert data == {'error': 'Unauthorized'}
+        assert 'details' not in data