We have library website written in classic ASP that allows to browse and search by multiple (50+) filter criterias (author, publication year, ISSN ... ). There are lots of security holes and we have only one developer who hardly maintain this ASP-site with some minor features for last 3 years. There are two common user groups - administrators (librarians) and students (5000+) who have books on hands and searches for them.

We don't want to rewrite it from scratch, just to use standard free CMS (.net based) and migrate library data and user accounts with minimum effort. What CMS will you suggest?

Thank you in advance.