: Using modified clients to send specific packets that trick the server into thinking the player has already authenticated. Recommended Mitigation Steps
: This is the most common exploit. If a server uses a proxy (like BungeeCord) but the individual "sub-servers" (Lobby, Survival, etc.) are not properly firewalled, an attacker can bypass the proxy and connect directly to a sub-server. Since the sub-server thinks the proxy already authenticated the player, AuthMe may not trigger.
Securing your server is about more than just installing the plugin; it requires a multi-layered defense strategy. AuthMe/AuthMeReloaded: The best authentication ... - GitHub
or attempting to bypass such security measures without authorization is generally against the terms of service of most Minecraft servers and can be considered a form of hacking or cheating.