From Adobe's PSIRT blog post:
A critical vulnerability exists in Adobe Reader and Acrobat 9.2 and earlier for Windows, Macintosh and UNIX operating systems. This vulnerability (CVE-2009-4324) could cause a crash and potentially allow an attacker to take control of the affected system.Adobe has also released a temporary fix for users to mitigate the situation until an official patch is released:
- Launch Acrobat or Adobe Reader.
- Select Edit>Preferences
- Click OK