None.
This project is no longer maintained. It used to be a hobby project of one person for 15 years, but even that basic substitute of a support is now gone.
If you discover a vunlerability, your best course of action is to migrate to other implementations, such as https://github.com/isc-projects/kea, which are maintained.
You may also open an issue. There is nobody to address a problem, but it might be useful to inform other users that the software they still use is vulnerable.