Investigate and report possible security issues, and help solve them before users are affected. Please don't do this on Framasoft's infrastructure but through installing the projects yourself.
The Framasoft GitLab instance is hosted at framagit.org. You have to sign-up here, using your e-mail account or by way of a third-party token provider.
Shortly after signup, you should receive a confirmation e-mail containing an activation link. Click it to activate your account. Request another one if you did not receive the e-mail within a few minutes.