Mass assignment in Masonite occurs when an application accepts a user-provided dictionary and passes it directly to a Model's create or update method without filtering. This allows attackers to overwrite sensitive fields—like 'is_admin', 'role', or 'balance'—by simply appending those keys to the JSON or form-data payload.

The Vulnerable Pattern

# Controller
def store(self, request: Request):
    # CRITICAL: This allows an attacker to pass {'is_admin': True} in the request
    user = User.create(request.all())
    return user
Model
class User(Model):
# No protection defined
pass

The Secure Implementation

To kill mass assignment, implement a two-layer defense. First, define the '__fillable__' attribute in your Masonite Model to whitelist only non-sensitive columns; this prevents the ORM from mapping unauthorized keys to the database. Second, in your Controller, never use 'request.all()'. Use 'request.only()' to strictly enforce that only the expected parameters reach the business logic. This ensures that even if a developer forgets to update the model whitelist, the entry point remains locked down.

# Model
class User(Model):
    # Define a whitelist of attributes that can be mass-assigned
    __fillable__ = ['username', 'email', 'password']
Controller
def store(self, request: Request):
# Explicitly filter inputs even if the model has fillable
user_data = request.only(‘username’, ‘email’, ‘password’)
user = User.create(user_data)
return user