CVE-2021-34527 Windows Print Spooler Vulnerability – How to Ensure Uninterrupted Printing Despite PrintNightmare

You may have recently become aware of  CVE-2021-34527, which has also been called PrintNightmare. It is a zero-day vulnerability impacting the Windows print spooler. Such a vulnerability may lead to an attacker taking remote control of an affected system. 

Follow these steps for secure printing until Microsoft releases its update. Image by Pete Linforth via Pixabay 

Currently, Microsoft aims to fix this security loophole on July 13, its next patch day. Until then, however, we recommend that ThinPrint customers take the following measures to ensure they can continue to print securely: 

  • Via a group policy, deactivate the setting Allow Print Spooler to Accept Client Connections. 
  • Until Microsoft releases an update, Map Additional Printers, as well as Windows Printer Mapping, should not be used.  

We recommend against deactivating the Print Service Spooler. This would mean that the use of ThinPrint may no longer be possible.  

July 9 Update:

Installation of patch causes problems on Zebra printers.

Apparently the installation of the security patch released by Microsoft (see July 7 Update below) causes Zebra printers and possibly other label printers to stop printing.

Microsoft and Zebra are already working on a fix, which is expected to be available in 1-2 days. If Zebra printers are in use, we strongly advise against installing the July 6 Microsoft patch.

July 7 Update:

Microsoft has now released an update which resolves the remote code issue:

“Updates a remote code execution exploit in the Windows Print Spooler service, known as “PrintNightmare”, as documented in CVE-2021-34527.”

For more details, visit the Microsoft support page.

We hope this information is of help to you, and now that the Microsoft update is released, we expect things to return to normal. If you have any further questions, don’t hesitate to contact us via our support channels

Robert Noonan
Robert Noonan
Robert Noonan has worked at Cortado Holding since 2010. Following his university studies, he worked in software and logistic companies in Ireland, Russia, Austria and Germany. He is resolute about getting to the heart of technology and communicating its benefits, allowing as many as possible to take advantage of the company’s products. Initially coming from a non-tech background, he believes the deciding factor for technology adoption and success remains a focus on simplicity, productivity and ease-of-use for all stakeholders. Robert Noonan holds a degree in International Business and Languages, specialising in international marketing. An avid traveller, he remains passionately interested in culture, language, food and volunteering.