WebGL is per definition not more unsafe than Microsoft Silverlight or Adobe Flash. So every browser with one of these "plugins" is potentially at risk - including Internet Explorer.
http://games.greggman.com/game/webgl-secur...osoft-bullshit/
I'm sorry, but I really doubt the credibility of the source. The maker seems to have several conspiracy theories against microsoft, here's one of the quotes:
QUOTEIt’s even more telling that Microsoft hired a firm, ContextIS, to create this bogus FUD so they’d have someone to hide behind. It’s pretty convenient that only a few minutes after ContextIS’s latest post Microsoft already had a well manicured response. If ContextIS had any credibility they’d be posting about the same issues on Silverlight5 (warning: might crash your machine), Flash 11 and Unity3D.