Nexuiz is a multi-player FPS game which uses a modified version of the Quake 1 engine.
Nexuiz fails to correctly validate input within "clientcommands". There is also a failure to correctly handle connection attempts from remote hosts.
Using a specially crafted "clientcommand" a remote attacker can cause a buffer overflow in Nexuiz which could result in the execution of arbitrary code. Additionally, there is a Denial of Service vulnerability in Nexuiz allowing an attacker to cause Nexuiz to crash or to run out of resources by overloading it with specially crafted connection requests.
There is no known workaround at this time.
All Nexuiz users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=games-fps/nexuiz-2.2.1"