
According to a report on Neowin, a member of the US Navy exploited a flaw in Microsoft Teams' code. Hypothetically it could be used by hackers to send malicious attachments to a Teams group from an outside source.
Alex Reid, a member of the US Navy's Red Team (a cybersecurity team within the Navy), published the "TeamsPhisher" tool on GitHub. The Red Team's stated purpose is to simulate hacker attacks and then create solutions to use in defense against these hacker attacks.