Quake II server before R1Q2, as used in multiple products, allows remote attackers to bypass IP-based access control rules via a userinfo string that already…

Quake II server before R1Q2, as used in multiple products, allows remote attackers to bypass IP-based access control rules via a userinfo string that already contains an "ip" key/value pair but is also long enough to cause a new key/value pair to be truncated, which interferes with the server's ability to find the client's IP address.