Server Crash Mod problem Help

[LayDown]

hey, I recently found out that people can join my server and do .crash on a hacked client and the server will crash
Does anyone know how to fix this

 

[Exodius1984]

Metro hacked client has this same feature attached to signs, it took one of my servers down and the only way I could fix it was to create a whole new world it was so bad. I'll be keeping an eye on this tread to see if anyone has a answer

 

[Produce]

When Mojang released the 1.8.6 version, they fixed the problem with the Sign Crash. Not sure if it will fix his problem ^, It will fix the sign crash. (Update to 1.8.6 or above)

How did I not know about this? I'm gonna go be savage on some servers now peace XD