I was doing some research on Content Delivery Networks. For those who don't know, a CDN is a large collection of servers that cache and quickly serve up static content such as images, css, js, etc, to end users. CDNs can significantly increase performance by not only caching content but by also limiting the number of network hops to retrieve content.
I'm considering using free CDNs but I was surprised to find next to zero articles, blogs, or forums concerning potential security risks when using them. What are the risks of using free CDNs? How are those risk mitigated?