Can External CSS Style Sheets Pose a Security Risk?

A website I frequent has recently asked its members not to use external CSS style sheets when customizing their lookups and profiles.

I was wondering why a website would do this, aside from wanting to limit what aesthetically may be changed. Customizing and using CSS is allowed and encouraged, so I know that isn't the reason why the request to not use them was made.

I also do not believe that cross browser compatibility is an issue in this case either, since on site CSS is still allowed.

Does an external CSS style sheet pose any sort of security risk or other treats I'm not aware of? I always assumed they were completely safe but is it possible to use them in a damaging way?

I'm just trying to figure out why the site might request this because I can not think of a concrete reason not to use them.

Well, basically everything can be a security risk.... but you probably know that.

External Style Sheets can pose security threats to a websites user; less commonly the remote server. They can be used as a gateway to inject certain types of hacks and so forth. CSS can be an easy way to hack data, but for more severe security risks it isn't really a standard threat.

Uuummm... That's the gist of it. So, yes, it can, but its more of a threat to a user and not a site itself. So I guess the site is looking out for its users and trying to make sure other members don't pick up something nasty off anothers profile

yes