Adobe strongly recommends upgrading to the latest Acrobat DC versions because Acrobat XI no longer receives security updates or technical support, leaving it vulnerable to modern threats. Adobe Help Center Key Fixes in Version 11.0.23
Although support had ended, this final "planned update" was released shortly after to provide critical security mitigations (APSB17-36) and bug fixes. Usage Risk: Download Adobe Acrobat Xi Pro 11.0.23 Fixed
This version addressed specific functional bugs alongside security patches: Accessibility: Adobe strongly recommends upgrading to the latest Acrobat
Fixed a bug where images in emails were converted to garbled text during PDF conversion. Stability: Download Adobe Acrobat Xi Pro 11.0.23 Fixed