This indicates an attack attempt against a heap-overflow vulnerability in Adobe Reader and Acrobat.
This vulnerability is caused by an error when the vulnerable software handles a PDF file that has malformed CFF font. A remote attacker may exploit this to execute arbitrary code.
Adobe Reader 9.3.1 and earlier versions for Windows, Macintosh, and UNIX
Adobe Acrobat 9.3.1 and earlier versions for Windows and Macintosh
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the latest update from the vendor.