Since it is a legacy version, standard "check for updates" menus may no longer work consistently.
This update is often cited by the community as a "fix" for persistent crashing issues seen in earlier XI versions. How to Download and Install Download Adobe Acrobat Xi Pro 11.0.23 Fixed
Resolved an issue where parts of images or text disappeared when using the Reading Order tool for figure/caption tagging. Since it is a legacy version, standard "check