Javascript lols on the bay of fleas!
What's that you say, ad-hoc script execution without using any alpha-numeric characters?
Yup:
http://thedailywtf.com/ar.cles/bidding-on-security blog.checkpoint.com/2016/02/02/ebay-platform-exposed-to-severe-vulnerability/
This is no crypto-breaking or man-in-the-middle style of exploitation, this is running ad-hoc java script directly on the client (i.e., your) machine by using a rather nasty JSF**k trick. The exploit could embed malicious code within legit fleabay pages which are delivered to you and neither the server nor you would be any the wiser.
Personally, I am going nowhere near fleabay until they've addressed the problem.