Microsoft Internet Security and Acceleration (ISA) Server 2004 logs unusual ASCII characters in the Host header, including the tab, which allows remote attackers to manipulate portions of the log file and possibly leverage this for other attacks.

DISPUTED Microsoft ISA Server 2004 allows remote attackers to bypass certain filtering rules, including ones for (1) ICMP and (2) TCP, via IPv6 packets. NOTE: An established researcher has disputed this issue, saying that "Neither ISA Server 2004 nor Windows 2003 Basic Firewall support IPv6 filtering ... This is different network protocol."

Microsoft Internet Security and Acceleration (ISA) Server 2004 allows remote attackers to bypass file extension filters via a request with a trailing "#" character. NOTE: as of 20060715, this could not be reproduced by third parties.