CGI versions before 5.00 for Perl allow Content-Disposition parameter injection via unescaped double quotes in the header attachment filename.
header(-attachment => $name) writes $name into the quoted filename parameter of Content-Disposition without escaping double quotes.
An application that passes request data as the attachment name can be made to send a second filename parameter, changing the name the response is saved under.
Upgrade to CGI 5.00 or later.