We generally only fully support the latest release. The same applies to exploits such as server crashes and item duplication bugs.
For serious exploits (duplication bugs, remote code execution, server/client crashes), open a private security advisory or contact the maintainers through GitHub Issues with minimal public detail until a fix is available.
For non-critical bugs, use the Issues tab on this repository.
If the issue also affects upstream Paper and is not Papyrus-specific, you may report it to PaperMC as well.