The remote host is missing an update to squirrelmail announced via advisory DSA 2291-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202291-1

Various vulnerabilities have been found in SquirrelMail, a webmail application. The Common Vulnerabilities and Exposures project identifies the following vulnerabilities: CVE-2010-4554 SquirrelMail did not prevent page rendering inside a third-party HTML frame, which makes it easier for remote attackers to conduct clickjacking attacks via a crafted web site. CVE-2010-4555, CVE-2011-2752, CVE-2011-2753 Multiple small bugs in SquirrelMail allowed an attacker to inject malicious script into various pages or alter the contents of user preferences. CVE-2011-2023 It was possible to inject arbitrary web script or HTML via a crafted STYLE element in an HTML part of an e-mail message. For the oldstable distribution (lenny), this problem has been fixed in version 1.4.15-4+lenny5. For the stable distribution (squeeze), this problem has been fixed in version 1.4.21-2. For the testing (wheezy) and unstable distribution (sid), these problems have been fixed in version 1.4.22-1. We recommend that you upgrade your squirrelmail packages.