Secunia

Dr_insane has reported some vulnerabilities in 1st Class Mail Server, allowing malicious people to view arbitrary files or conduct Cross Site Scripting attacks.

1) An input validation error can be exploited to access directories outside the web root via the URL encoded representation of the "..//" directory traversal character sequence.

2) Certain input isn't properly verified before being returned to the user. This can be exploited to execute arbitrary HTML or script code in a user's browser session in context of an affected site by tricking the user into visiting a malicious website or follow a specially crafted link.

Examples:
/AUTH=[some_value]/user/viewmail.tagz?Site=[some_site]&Mailbox=3&MessageIndex=[malicious_code]>
/AUTH=[some_value]/user/?Site=[some_site]&Mailbox=[malicious_code]
/AUTH=[some_value]/user/members.tagz?Site=[some_site]&Mailbox=[malicious_code]
/AUTH=[some_value]/user/general.tagz?Site=[some_site]&Mailbox=[malicious_code]
/AUTH=[some_value]/user/advanced.tagz?Site=[some_site]&Mailbox=<[malicious_code]>
/AUTH=[some_value]/user/list.tagz?Site=[some_site]&Mailbox=[malicious_code]

This has been reported in version 4.01. Other versions may also be affected.

Solution
Use another product.
Further details available in Customer Area

Provided and/or discovered by
Dr_insane

Changelog
Further details available in Customer Area

Original Advisory
http://members.lycos.co.uk/r34ct/main/1st%20Class%20mail%20server%204.01.txt

Deep Links
Links available in Customer Area