All news with #teams guest access tag
Fri, November 28, 2025
Microsoft Teams guest access can bypass Defender protections
⚠️ Researchers warn a cross-tenant blind spot in Microsoft Teams can allow attackers to sidestep Microsoft Defender for Office 365 when users accept guest access in another tenant. Protections follow the hosting tenant, not the user's home organization, enabling attackers to create protection-free malicious tenants using low-tier licenses. Organizations should restrict B2B invitations, enable cross-tenant access controls, and train users to reject unsolicited guest invites.