The most supported version will always be the top most major version (X.x.x) and the top most minor version (x.X.x). It is recommended to be on the latest bug fix version of course, if you aren't you should keep it mind there may be issues with your release.

We've changed build systems since 0.2.X, so it is important to use 0.3.0 and up.

Creating an issue with information about the vulnerability is appreciated.