It is highly recommended not to use Adobe Reader XI on an internet-connected modern computer. Because support ended in 2017, the software contains unpatched security vulnerabilities. Cybercriminals often exploit known flaws in outdated PDF readers to deliver malware. Modern alternatives should be used for security purposes.
Acrobat XI Deployment Guide for Large Firms - the Adobe Blog adobe readerxi
To run Adobe Reader XI in 2012, systems needed to meet the following minimum specifications: It is highly recommended not to use Adobe