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.

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 restrict acceptable values for the language parameter to mail/settings.html before it is stored in a database, which can allow remote authenticated users to include arbitrary PHP code via a URL in a modified lang_settings parameter to mail/index.html.

dir/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, allows remote attackers to include arbitrary local files via a null byte (%00) in the lang parameter, possibly due to a directory traversal vulnerability.

PHP remote file include vulnerability 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, when register_globals is enabled, allows remote attackers to include arbitrary local and remote PHP files via a URL in the (1) lang_settings and (2) language parameters in (a) accounts/inc/include.php and (b) admin/inc/include.php.