Cross-site scripting (XSS) is an attack where a malicious actor is able to send untrusted data to a user's browser without going through any validation or sanitization processes, or perhaps the code is not properly escaped from processing by the browser. The code is then executed on the user's browser with their own access and permissions, allowing the attacker to redirect the user's web traffic, steal data from their session, or potentially access information on the user's own computer that their browser has the ability to access. Missing function-level access control exists where an application only checks for authorization during the initial login process and does not further validate with each function call. An injection attack is where a malicious actor sends commands or other arbitrary data through input and data fields with the intent of having the application or system execute the code as part of its normal processing and queries.
Cross-site request forgery occurs when an attack forces an authenticated user to send forged requests to an application running under their own access and credentials.