Mandriva Linux Security Advisory 2010-120 – A vulnerability was reported in the SquirrelMail Mail Fetch plugin, wherein (when the plugin is activated by the administrator) a user is allowed to specify (without restriction) any port number for their external POP account settings. While the intention is to allow users to access POP3 servers using non-standard ports, this also allows malicious users to effectively port-scan any server through their SquirrelMail service (especially note that when a SquirrelMail server resides on a network behind a firewall, it may allow the user to explore the network topography (DNS scan) and services available (port scan) on the inside of (behind) that firewall. As this vulnerability is only exploitable post-authentication, and better more specific port scanning tools are freely available, we consider this vulnerability to be of very low severity. It has been fixed by restricting the allowable POP port numbers. The updated packages have been patched to correct this issue.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/90891/MDVSA-2010-120.txt
Source: https://packetstormsecurity.com/files/90891/Mandriva-Linux-Security-Advisory-2010-120.html