Buffer overflow in the UGameEngine::UpdateConnectingMessage function in the Unreal engine 1, 2, and 2.5, as used in multiple games including Unreal Tournament 2004, Unreal tournament 2003, Postal 2, Raven Shield, and SWAT4, when downloads are enabled, allows remote attackers to execute arbitrary code via a long LEVEL field in a WELCOME response to a download request.

The Unreal engine, as used in Unreal Tournament 3 1.3, Unreal Tournament 2003 and 2004, Dead Man's Hand, Pariah, WarPath, Postal2, and Shadow Ops, allows remote authenticated users to cause a denial of service (server exit) via multiple file downloads from the server, which triggers an assertion failure when the Closing flag in UnChan.cpp is set.

Directory traversal vulnerability in manifest.ini in Unreal engine allows remote attackers to overwrite arbitrary files via .. (dot dot) sequences in a UMOD (Unreal MOD) file.

The Unreal Engine, as used in DeusEx 1.112fm and earlier, Devastation 390 and earlier, Mobile Forces 20000 and earlier, Nerf Arena Blast 1.2 and earlier, Postal 2 1337 and earlier, Rune 107 and earlier, Tactical Ops 3.4.0 and earlier, Unreal 1 226f and earlier, Unreal II XMP 7710 and earlier, Unreal Tournament 451b and earlier, Unreal Tournament 2003 2225 and earlier, Unreal Tournament 2004 before 3236, Wheel of Time 333b and earlier, and X-com Enforcer, allows remote attackers to execute arbitrary code via a UDP packet containing a secure query with a long value, which overwrites memory.

Epic Games Unreal Engine 226f through 436 allows remote attackers to cause a denial of service (CPU consumption or crash) and possibly execute arbitrary code via (1) a packet with a negative size value, which is treated as a large positive number during memory allocation, or (2) a negative size value in a package file.

Unreal Tournament 2003 (ut2003) clients and servers allow remote attackers to cause a denial of service via malformed messages containing a small number of characters to UDP ports 7778 or 10777.