WatchGuard SOHO products running firmware 5.1.6 and earlier, and Vclass/RSSA using 3.2 SP1 and earlier, 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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2002-1979
• http://www.kb.cert.org/vuls/id/328867
• http://www.kb.cert.org/vuls/id/AAMN-5EQR65