There is a recently discovered critical vulnerability that affects all Matrix homeservers of the Conduit lineage. If you’re using a Rust-based Matrix server (which are basically Conduit and forks), please urgently upgrade to the following versions:

If you’re not able to upgrade right now, you should urgently implement this workaround in your reverse proxy.

Attackers exploiting this flaw can arbitrarily kick any user out of a room, join rooms unauthorized on the same server, and can also ban same-server users. They effectively constitute a severe denial of service from an unauthenticated party, and it has been exploited in the wild.