Using scripts in your account that are insecure (vulnerabilities unpatched) is very dangerous. Doing so runs the risk of account suspension or exploit from a third party which can cause total account compromise, data loss or account suspension/termination (if used by the person for warez, spam, etc).
Therefore, it is extremely important that all scripts in use are the latest version and secure.
A good way of determining whether a script is secure is to type the script name into http://www.google.com along with the word "exploit" which will bring up any security topics associated with the script that can be researched. For example, a search on PHP-Nuke can be seen here.