Windows 11 June Patch Triggers Microsoft Office Startup Issues

Microsoft's June 2026 cumulative update for Windows 11 (KB5095051, OS Build 28000.2269) includes security hardening and reliability changes but has introduced an application compatibility bug that can stop Office apps (Word, Excel, Outlook) from launching when invoked by third-party integrations. The issue appears tied to tightened execution/trust handling in the OS; Microsoft has not published a mitigation timeline, so affected organizations should monitor integrations, temporarily launch Office apps directly, or roll back the update on critical systems until a fix is available.