Valve Software » Half-life : Security Vulnerabilities, CVEs, CVSS score >= 1

The Half-Life engine before July 7 2004 allows remote attackers to cause a denial of service (server or client crash) via an empty fragmented packet.

Half-Life Server 1.1.1.0 and earlier allows remote attackers to cause a denial of service (resource exhaustion) via multiple responses to the initial challenge with different cd_key values, which reaches the player limit and prevents other players from connecting until the original responses have timed out.

Buffer overflow in client for Half-Life 1.1.0.8 and earlier allows malicious remote servers to execute arbitrary code via a long console command.

Buffer overflows in Sierra Half-Life build 1573 and earlier allow remote attackers to execute arbitrary code via (1) a long map command, (2) a long exec command, or (3) long input in a configuration file.