This patch fixes an in-the-wild exploit. Adobe Reader X has the same vulnerability but in its default configuration has protections which prevent the exploit from working. If you have AR9, PATCH NOW. If you have AR X, make sure your settings are configured properly. Foxit Software has issued a press release claiming their software is not affected by this flaw.
While these vulnerabilities exist in Adobe Reader X (10.1.1) and earlier versions for Windows and Macintosh, Adobe Reader 9.4.6 and earlier 9.x versions for UNIX, and Adobe Acrobat X (10.1.1) and earlier versions for Windows and Macintosh, there is no immediate risk to users of Adobe Reader and Acrobat X for Windows (with Protected Mode/Protected View enabled), Adobe Reader and Acrobat X or earlier versions for Macintosh, and Adobe Reader 9.x for UNIX based on the current exploits and historical attack patterns.
Today's updates address these vulnerabilities in Adobe Reader and Acrobat 9.x for Windows. Adobe recommends users of Adobe Reader 9.4.6 and earlier 9.x versions for Windows update to Adobe Reader 9.4.7. Adobe recommends users of Adobe Acrobat 9.4.6 and earlier 9.x versions for Windows update to Adobe Acrobat 9.4.7.FREMONT, Calif. - December 14, 2011 - Foxit® Corporation, a leading provider of solutions for reading, editing, creating, organizing, and securing PDF documents, today announced that the Foxit Reader is not vulnerable to the latest zero-day (CVE-2011-2462) vulnerability. Users who are concerned about this much publicized issue should feel safe in downloading the Foxit Reader to meet their PDF reader requirements.