The newest version release is the only version actively being supported. Security issues with older version can still be reported, and notes will be added to their release notes.
Please report all security vulnerabilities in the Security Tab. I will prioritize investigation and resolving security issues over feature or bug fix commits, and respond as soon as I've had time to investigate. If I can reproduce the conditions needed for an exploit, a patch release will be created shortly after.
If a library this project depends on contains a security vulnerability, reports specifying that the currently used version of the library is out of date, or an alternative library exists that does not have a vulnerability will be investigated and acted on.