Security watchers are warning of a serious unpatched vulnerability in Adobe's Reader program that's actively being exploited to install malware on the PCs of unsuspecting users.

The vulnerability has been confirmed in versions 8.1.3 and 9.0.0 of Adobe Reader running on Windows XP Service Pack 3 and is presumed to work on other versions of Windows as well, according to this advisory from Shadowserver. Adobe for machines running Linux and Apple's OS X were not tested, but may also be vulnerable, Shadowserver's Steven Adair said. More at; http://www.theregister.co.uk/2009/02/20/adobe_reader_exploit/