Using the GitHub Vulnerability reporting system enables multiple responders without needing to manage PGP/GPG key encryption.
https://github.com/radvd-project/radvd/security/advisories/new
Please send GPG-encrypted email to robbat2@gentoo.org.
Preferred key for encryption is 0x31577DE43D517E25CB1DCDF1EA2637A12FBBD6F8 (sub-key to 0x7D0B3CEBE9B85B1F825BCECFEE05E6F6A48F6136).