Format string vulnerability in the Cio_PrintF function of cio_main.c in Unreal IRCd 3.1.1 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via format string specifiers.

The IP cloaking feature (cloak.c) in UnrealIRCd 3.2, and possibly other versions, uses a weak hashing scheme to hide IP addresses, which could allow remote attackers to use brute force methods to gain other user's IP addresses.

UnrealIRCd 3.2.3 allows remote attackers to cause an unspecified denial of service by causing a linked server to send malformed TKL Q:Line commands, as demonstrated by "TKL - q\x08Q *\x08PoC."