Only the latest version is currently supported with security and bug fixes.
If there are major/minor versions which will be used in the future, I will ensure to support them also with security and bug fixes. If there are plans to use the library in your projects, feel free to contact me and let me know about it so I can ensure the support.
If you find a vulnerability, please create a new Security Advisory with the details.
I will give immediately feedback at the latest after 24 hours.