Adobe Reader XI is an older version of Adobe Acrobat Reader, a free software application for viewing and interacting with PDF (Portable Document Format) files on Windows. It[SQ]s no longer supported by Adobe, meaning it doesn[SQ]t receive security updates or bug fixes. This makes it a significant security risk.

It[SQ]s strongly advised to not use Adobe Reader XI and instead update to the latest version of Adobe Acrobat Reader DC.

Using an unsupported version leaves your system vulnerable to malware and exploits.