Russian hackers have worked out a way that they can gain free access to Ubisoft's online game offerings.
According to Game Informer, the hack highlights the problems for games companies who put their products online. Rather than spending a lot of time hacking into game DRM, the hackers can focus on breaking into the defences of the online servers. They can then illegally sell access.
A Ubisoft spokesperson said that the company was aware of the problem and is working to resolve it quickly.
While no personal information was compromised, uPlay's PC download service will be unavailable until the problem is fixed.
In this case the hack tricked uPlay into thinking users already own a particular game, making it available to download at no cost and with no DRM.
What will be embarrassing for Ubisoft is that its unannounced shooter Far Cry 3: Blood Dragon is apparently lying on Ubisoft's servers, available to download to those who have the exploit.
All was revealed when someone using the hack posted half an hour of Blood Dragon footage on YouTube.
While this was quickly pulled down by Ubisoft, it was really being shown as evidence that the exploit works and is being used to play the unreleased game.