Adobe has released updated versions of Adobe Reader and Adobe Acrobat that fix critical security issues that affect Windows systems. These critical security issues could cause the application to crash and potentially allow an attacker to take control of the affected system. Please update your systems running Acrobat or Reader version 9.4.6 (or earlier) as soon as possible.
More information, as well as links to software updates from Adobe, is available here:
Note that while Acrobat and Reader X (10.1.1) are also vulnerable, version X would prevent an exploit of the type currently targeting these vulnerabilities from executing. Adobe intends to address these issues in Adobe Reader and Acrobat X for Windows with the next quarterly security update, scheduled for January 10, 2012.