mail/include.html in IceWarp Web Mail 5.5.1, as used by Merak Mail Server 8.3.0r and VisNetic Mail Server version 8.3.0 build 1, does not properly initialize the default_layout and layout_settings variables when an unrecognized HTTP_USER_AGENT string is provided, which allows remote attackers to access arbitrary files via a request with an unrecognized User Agent that also specifies the desired default_layout and layout_settings parameters.
Use Deerfield vendor hub and Visnetic Mail Server product page to widen CVE-2005-4559 into its surrounding weakness, vendor, and product context.
Compare it with CVE-2005-4556, CVE-2005-4558 and CVE-2006-0817 for nearby disclosures in the same product family.