[German]The June 2025 security updates for Microsoft Office fixes critical vulnerabilities, but appear to cause serious problems for some users in corporate environments. Document files can no longer be opened in the Office applications. There are also reports of crashes and problems with Microsoft Outlook Classic. Addendum: Outlook crashes have been confirmed by Microsoft, there is a workaround.
Office Updates June 2025
On June 10, 2025, various security updates were released for the Office versions currently under support (see Patchday: Microsoft Office Updates (June 10, 2025)). Prompt installation is important as the remote code execution vulnerabilities CVE-2025-47162, CVE-2025-47164, CVE-2025-47167 and CVE-2025-47953, which are classified as critical with a CVEv3 score of 8.4, are closed by the updates (see also Microsoft Security Update Summary (June 10, 2025)). With the exception of CVE-2025-47953, a display in the preview window is sufficient as an attack vector to exploit these vulnerabilities. Microsoft therefore rates the exploitability as "Exploitation More Likely".
Outlook Classic causes issues / crashes
After the June 2025 patchday, German readers have reported problems with Outlook Classic in corporate environments within my blog.
Outlook 2021 LTSC crashes
In this German comment, blog reader SWE describes a crash of Outlook Classic in Microsoft Office 2021 LTSC when handling emails. Double-clicking on an email or creating a new email is enough to cause Outlook to crash immediately. The reader writes that there are no entries about the crash in the event log. The reader's remedy was to go back to build 14332.21040.
German reader Frank also reported in this comment about crashes with replies, calendar entries etc. of the Office 2021 LTSC (German version) used. Reverting to the previous version fixes the problem, but then the vulnerabilities are not fixed.
Outlook 2016 also affected, update KB5002683 as the cause
The above description of Outlook 2021 is not an isolated case, but has also been confirmed by several readers for Outlook 2016. In this German comment, Troi writes that their Windows 10 clients with Office 2016 are experiencing the Outlook Classic crashes mentioned above.
Another anonymous reader confirms that he has received some reports of crashes when clicking on "New Mail" in Outlook. In the environment with Windows 10 and Microsoft Office 2016, only certain users are affected.
In the meantime, the security update KB5002683 (for Outlook 2016, which fixes the RCE vulnerability CVE-2025-47171) has emerged as the culprit in this scenario.
Sporadic error ?
There seems to be a "very problematic error pattern". Reader Henry writes here that the crashes occur "only sporadically" due to the aforementioned update. He states that "in the middle of operation, Outlook/Office 2016 start to close and no longer open". However, there are entries in the event log that confirm the App Crash error. Even stranger: Outlook or the Office application should start again at some point. This is independent of reboots, occurs via RDS with mandatory profiles, notebooks with local profiles, etc.
Support article confirms Outlook 2019 problems
In this comment, German blog reader MBDTeam refers to the Microsoft support article Outlook LTSC 2019 crashes opening Viva Engage, Yammer, Power Automate, and other emails. There, Outlook LTSC 2019 crashes are already confirmed with the date June 9, 2025, i.e. before the Office Patchday. The solution is to use OWA or the new Outlook app.
Office documents cannot be loaded
German blog reader Paul writes in this comment that after installing the June 2025 updates, there are problems with opening documents in Office applications. Office documents that are saved in the download folder, for example, can no longer be opened with the Office applications. These documents can still be opened in the Office portal (Online Office) without any problems.
To open the file, access must be allowed in the file properties (right-click on the document file, then select Properties in the context menu and set the Allow option on the Security tab, then confirm by clicking OK or Apply.
The SmartScreen function of the Defender does not seem to be the cause of the loading problems, as readers have suggested. Another user Joshi confirms the problem that documents can no longer be opened automatically and have to be released manually by the user via a workaround.
Microsoft confirms Outlook crashes, workaround available
Addendum: On June 13, 2025 Microsoft published the support article Classic Outlook crashes opening or starting a new email regarding the Outlook email crash bug. It confirms the bug and states that the problem has been escalated and is being investigated. The problem occurs in the monthly Enterprise Channel from version 2504 (build 18730.20122) because Outlook cannot open the Forms Library. Virtual desktop infrastructures (VDI) are affected. Currently a workaround of the type "add a folder" is suggested. I've compiled the details about the workaround and more information within the blog post Outlook crashes caused by June 2025 Updates confirmed with workaround
Similar articles:
Microsoft Security Update Summary (June 10, 2025)
Patchday: Windows 10/11 Updates (June 10, 2025)
Patchday: Windows Server-Updates (June 10, 2025)
Patchday: Microsoft Office Updates (June 10, 2025)
Windows 10/11: Preview Updates May 27, 28,2025
Attention: June 2025 Patchday closes vulnerability CVE-2025-33073 in Windows
