Enclave: a single debug flag left on in six Microsoft 365 Android apps allowed silent OAuth-token theft

Researchers at Enclave found a shared Android SDK across six Microsoft 365 apps shipped setIsDebugMode(true) in production, disabling the AccountManager check that restricts token sharing to trusted Microsoft apps — so any co-installed third-party app could silently obtain long-lived OAuth tokens for the signed-in Microsoft identity with no prompt (SecurityWeek, 2026-06-02 · The Hacker News, 2026-06-03). Affected: Word (CVE-2026-41101), PowerPoint (CVE-2026-41102), Excel (CVE-2026-42832), Microsoft 365 Copilot (CVE-2026-41100), Loop and OneNote — collectively billions of installs; Teams was unaffected because its flag was correctly false. Tokens granted read/write to Exchange mail, OneDrive and Calendar. Microsoft fixed all six in the 12 May 2026 cycle; no ITW reported pre-patch. Enforce minimum-version compliance for these apps via Intune/MDM on BYOD fleets and, where logs exist, review AccountManager token requests from non-Microsoft packages.