Course

In this lab, you are presented with the vulnerable code and the corresponding patch. The goal is to identify the security flaw on your own before using the patch as a reference. The provided code snippet is from the `StatelessTokenService` class in a Java project, which is responsible for generating and validating JWT tokens. The vulnerable code allows you to understand the issue deeply, while the patch demonstrates the correct way to fix it.

The vulnerable code handles JWT tokens but lacks a crucial validation step for the token's signing algorithm, making it susceptible to certain types of attacks. The patch introduces a new method to validate the token algorithm and modifies the token parsing logic to include this validation step, thus securing the service against potential misuse. By comparing the two, you can gain a deeper understanding of both the vulnerability and the appropriate remediation.