Microsoft Teams will let admins block custom file extensions

Microsoft Teams will let admins customize blocked file extensions in Weaponizable File Protection, rolling out globally from November 2026 across all platforms.

Microsoft is expanding admin controls for the Weaponizable File Protection feature in Teams, letting administrators customize the list of blocked high-risk file extensions instead of relying only on Microsoft's recommended default list. The capability is in development per the Microsoft 365 roadmap, with rollout beginning November 2026 across Android, desktop, iOS, macOS, and web for standard multi-tenant cloud environments. Microsoft also announced complementary Teams defenses: blocking external users via the Defender portal starting December, blurring QR codes from external senders, reporting suspicious guest invitations from November, and automatically blocking external bots from meetings.