PDF load freezes IE 11 with adobe acrobat reader (reader version 2022.001.20117)

[Andrew Hodge]

Morning, 

Issue 

We are experiencing an issue across our server and pc estate where when viewing PDFs using internet explorer 11 with adobe acrobat reader (reader version 2022.001.20117) (IE plugin version 21.11.20039.0) in an iframe.  The web application re-uses the HTML iframe to load different PDFs from our web based document storage.  Loading the 1st PDF in the iframe works as expected, Loading the 2nd PDF in the iframe now hangs at the initializing stage.  

This is a legacy web application we have been using for circa 15 years, the issue has only started since updating to the latest version of acrobat reader (2022.001.20117).  PCs still running older versions of the acrobat reader do not experience this issue. 

Disabling enhanced security via the Security (Enhanced) preferences or using the registry key bEnhancedInBrowser prevent the issue occuring but this is not a workaround we can implement due to infosec requirements. 

We do not experience the issue when opening the PDF in a new IE window (not an iframe).   

Have attached a short video of the issue.   Opening first pdf works as expected, opening 2nd pdf hangs at initialising stage.  

[Andrew Hodge]

As additional reverting to the previous versions of the ActiveX dlls prevents this issue.  So something specifically related to AcroPDFImpl.dll and AcroPDFImpl64.dll with version 22.1.20117.0