This indicates an attack attempt to exploit a Memory Corruption vulnerability in Adobe Reader and Acrobat.
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 execute arbitrary code within the context of the application, via a crafted PDF file.
Acrobat DC 15.020.20039 on Windows and Macintosh
Acrobat Reader DC 15.020.20039 on Windows and Macintosh
Acrobat DC 15.006.30243 on Windows and Macintosh
Acrobat Reader DC 15.006.30243 on Windows and Macintosh
Acrobat XI 11.0.18 on Windows and Macintosh
Reader XI 11.0.18 on Windows and Macintosh
System Compromise: Remote attackers can gain control of vulnerable systems.
Upgrade to the latest version available from the website.