Post spam

I have a site that seems to be experiencing spam being injected within the posts. I have a lot of WordPress sites up and running, and this is a first for me. I’ve seen comments with spam, but never posts, and not in this particular way. I’ve highlighted the comments in one of the posts (see screenshot below).

http://www.screencast.com/t/b97Z9o1ii

I’m thinking that this is an issue on the user’s end, since only posts are affected (not pages), but since I’ve never seen anything like this before, I thought I’d ask.

Has anyone else experienced this? Any solutions?

Thank you in advance!

Alex T