This indicates an attack attempt to exploit a Security Bypass Vulnerability in Adobe Acrobat Reader.
The vulnerability is due to an error when the vulnerable software handles a maliciously crafted PDF file. A remote attacker may be able to exploit this to bypass security checks on vulnerable systems, via a crafted PDF file.
Adobe Reader XI (11.0.11) and earlier 11.x versions
Adobe Reader X (10.1.14) and earlier 10.x versions
Adobe Acrobat XI (11.0.11) and earlier 11.x versions
Adobe Acrobat X (10.1.14) and earlier 10.x versions
Security Bypass: Remote attackers can bypass security checks of vulnerable systems.
Refer to the vendor's advisory for updates: