We recently discovered a serious vulnerability within MTA Server, as a result of which a specially crafted application could crash your server. The issue has been fixed and we urge all server owners to update immediately.
Getting the update
Windows x64: https://nightly.mtasa.com/?mtasa_x64-1.5.6-rc-latest
Re-download the full installer from http://mtasa.com for the regular x86 server
Please note that any server currently on 1.5.6 (or 1.5.x) but not yet on the revision of 1.5.6 we released today, is vulnerable.
Keeping you safe and secure .
-- MTA Team