5 Million users on Steam are exposed to multiple holes in the Steam client's security, explained here. (via ReVuln)

ReVuln - Steam Browser Protocol Insecurity from ReVuln on Vimeo.
In this video we will demonstrate a novel and interesting way to convert local bugs and features in remotely exploitable security vulnerabilities by using the well known Steam platform.
The research paper: "Steam Browser Protocol Insecurity (when local bugs go remote)", can be found at:
http://revuln.com/files/ReVuln_Steam_Browser_Protocol_Insecurity.pdf
