While pointing out that Twitter was not the proper communication channel to report security vulnerabilities, I've not been able to locate a procedure on how security vulnerabilities should be reported.
Quick summary of a following IRC conversation: the past approach has been for people to gpg-encrypt their mail to one of me, nickm, ioerror, or whoever else they think is the sole member of the tor project (arma). That could be documented right now.
But that's not a great approach. i guess another option is for us to create a tor-security gpg key and share it across said people (arma), so we could call it tor-security@tp.o (arma), who's "we"?, you, me, athena, mikeperry, and somebody? (nickm), works for me (arma).
But it needs to not be a 'cool kids club (arma) and an explicit set of critera might be better.
So maybe the right thing to do is to combine both roles behind one email address (which will probably lead to more work / more hassle for us internally, but it would make things easier for outsiders).
If someone can add the key I can update the Contact page.
As for the mailing list wiki page, I'm thinking it should it go under Administrative Lists rather than down with network-team-security@ under Encrypted Lists.