At the moment, the only supported version of the HandyControl is the newest one. You can find it on NuGet.
https://www.nuget.org/packages/HandyControl/
Security issues and bugs should be reported privately, by emailing support (at) HandyOrg HandyOrg does not offer Bug Bounty for the HandyControl library.
Please do not open issues for anything you think might have a security implication.