Black Duck Open Hub has launched a "Project Vulnerability Report" (PVR) score. This is an excellent initiative, and quite a challenge (given the messy data).
About this project:
The results for Tiki are here: https://www.openhub.net/p/tikiwiki/security
Discussion is here: https://www.openhub.net/topics/13907
As of 2016-11-26, there is an issue with the data, to be reported: