over an existing 11.0.x installation, as the full standalone installer for 11.0.23 was never widely released. official documentation
Why can't I add text to comments to PDF files in Adobe Reader XI? adobe reader xi version 11.0.23
Adobe Reader XI version 11.0.23 represents the conclusion of a specific era in software history—the era of the standalone, perpetual-license desktop utility. While it offered a robust set of features and introduced critical sandboxing technologies that changed the security landscape, its utility has expired. over an existing 11
If the PDF is not a fillable form, you can still "prepare" or overlay your own text: Open the Tool : Click the pane on the right side of the window. Select the Tool : Expand the Annotations panel and choose the Add Text Comment tool (represented by a "T" icon). Place and Type While it offered a robust set of features
As a cumulative security and bug-fix update, it includes all enhancements introduced throughout the XI lifecycle: Adobe Security Bulletin
Isolate Reader XI 11.0.23 inside a Windows 7 virtual machine (VM) with no network access. Use a shared folder to transfer sanitized PDFs into the VM. This preserves the lightweight feel while creating a security buffer.