Hundreds of thousands of redeemable code for Codemasters' Dirt 3 have been leaked through a website belonging to AMD.
The codes were in possession of AMD4u website as part of a promotion where they are granted to purchasers of specific AMD cards. There are no details yet about the number of leaked codes or how they were leaked.
The entire list of codes has been posted on several forums, but it shouldn't be a surprise that they have been blocked by Steam already.
Codemasters and AMD released separate statements regarding the matter, asserting that their servers were not compromised (it was a third party hired by AMD whose servers were compromised) and that legitimate codes will be honored, albeit after a short delay to sort them out.