IPFilter 3.1.1 through 3.4.28 allows remote attackers to bypass firewall rules by sending a PASV command string as the argument of another command to an FTP server, which generates a response that contains the string, causing IPFilter to treat the response as if it were a legitimate PASV command from the server.

IPFilter 3.4.25 and earlier sets a different TTL when a port is being filtered than when it is not being filtered, which allows remote attackers to identify filtered ports by comparing TTLs.

IPFilter 3.4.16 and earlier does not include sufficient session information in its cache, which allows remote attackers to bypass access restrictions by sending fragmented packets to a restricted port after sending unfragmented packets to an unrestricted port.

Race condition in IPFilter firewall 3.4.3 and earlier, when configured with overlapping "return-rst" and "keep state" rules, allows remote attackers to bypass access restrictions.

IPFilter 3.2.3 through 3.2.10 allows local users to modify arbitrary files via a symlink attack on the saved output file.