Adobe has released updated versions of Adobe Reader and Adobe Acrobat that fix issues including several critical security issues that affect Windows, Macintosh, and UNIX systems. The critical security issues could cause the application to crash and potentially allow an attacker to take control of the affected system.
Three different versions of the update of available dependent upon the currently installed version of Acrobat or Reader installed: Adobe Reader X (10.0.1), Adobe Reader 9.4.2 and Adobe Reader 8.2.6.
Note that the UNIX version of the Adobe Reader 9.4.2 update is expected to be available by the week of February 28, 2011.
More information is available here: http://www.adobe.com/support/security/bulletins/apsb11-03.html