Microsoft has acknowledged a new compatibility issue with Trellix’s endpoint security software and some Windows 11 and Windows 10 devices. The company detailed on the Windows Health dashboard that the bug prevents users from opening Microsoft Office and third-party apps.
According to Microsoft, the problem is caused by the latest Patch Tuesday updates released on June 13. The company says that some users who installed the recent OS updates were unable to launch Microsoft Outlook, other Office apps, and third-party software. The problem affects Windows 11 versions 21H2 and 22H2, Windows 10 versions 21H2 and 22H2, as well as Windows Server 2022.
“This issue only occurs with 32-bit apps running on 64-bit Windows with Trellix Endpoint Security version earlier than 35.31.25. When attempting to open an affected app, Event Log indicates an access violation with the error “module is unknown”. This issue is not likely to be encountered by consumers using Windows devices in their home,” Microsoft explained.
Microsoft recommends customers to update Trellix Endpoint Security Agent to version 35.31.25 and newer to mitigate the compatibility issue on Windows 11 and 10 devices. Meanwhile, customers who are experiencing problems with other anti-malware apps are advised to contact their security software providers.
Furthermore, some users reported that the KB5027231 security update blocks access to Google Chrome on Windows PCs. Malwarebytes confirmed that its Exploit Protection module prevents users from fully loading the web browser. The KB5027231 update is also incompatible with security solutions from Cisco, and WatchGuard.
Trellix, Malwarebytes, and WatchGuard have released security patches to address the known issue on affected Windows systems. However, Cisco is still working on a fix and advises users to set Google Chrome as the default web browser or disable anti-exploit protection in the settings of their security solution.