As of November 2019 (and until this document is updated), only the v3.0.0-beta tags of Strapi are supported for updates. Any previous versions are currently not supported and users are advised to use them "at their own risk".
Reporting a Vulnerability
When reporting a (suspected) security vulnerability via slack please reach out to any of the following Strapi employees directly:
You will receive a response from us within 72 hours. If the issue is confirmed, we will release a patch as soon as possible depending on complexity but historically within a few days.