In cooperation with Certified Secure, 42 has released a showcase that will help you understand the documented vulnerabilities of Spring. Learning more will allow you to harden your applications against this particular attack vector.
In an earlier article, it has been shown how a Spring vulnerability can be turned against you if you are not careful enough. Now you can actually try it out yourself. You do not have to create a CertifiedSecure account to play the assignment. You only have to create an account if you want to claim the reward.
Be sure to read up on the article and the documented vulnerabilities, if you want to know more about the background. If you still want to know more, know that we will be attending GOTO Amsterdam June 18/19 and will gladly have a chat with you on the topic. In the meantime, happy hunting!