A critical vulnerability has been identified in Adobe Reader 9.1 and Acrobat 9.1 and earlier versions. This vulnerability (CVE-2009-1492) would cause the application to crash and could potentially allow an attacker to take control of the affected system.
A second vulnerability has also been reported that appears to affect Adobe Reader for UNIX only (CVE-2009-1493). These issues are remotely exploitable.
Adobe categorizes this as a critical update and recommends that users apply the update for their product installations.