A computer-implemented method, apparatus, and article of manufacture for security validation of a user input in a computer network application. The method includes: providing a subset of security rules of a server-side protection means to a pre-validation component deployed at a client side, so as to enable security validation of a user input on the client side by the pre-validation component; validating the user input based on at least one of the security rules; determining, in response to detecting a user input violation and that a violated security rule has not been provided to the pre-validation component, the user as a first class of users; determining, in response to detecting the user input violation and that the violated security rule has been provided to the pre-validation component, the user as a second class of users; and performing different security protection actions to the first and second class of users.