The remote host is missing an update to squirrelmail announced via advisory DSA 1802-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201802-1

Several remote vulnerabilities have been discovered in SquirrelMail, a webmail application. The Common Vulnerabilities and Exposures project identifies the following problems: CVE-2009-1578 Cross site scripting was possible through a number of pages which allowed an attacker to steal sensitive session data. CVE-2009-1579 Code injection was possible when SquirrelMail was configured to use the map_yp_alias function to authenticate users. This is not the default. CVE-2009-1580 It was possible to hijack an active user session by planting a specially crafted cookie into the user's browser. CVE-2009-1581 Specially crafted HTML emails could use the CSS positioning feature to place email content over the SquirrelMail user interface, allowing for phishing. For the old stable distribution (etch), these problems have been fixed in version 1.4.9a-4. For the stable distribution (lenny), these problems have been fixed in version 1.4.15-4+lenny1. For the unstable distribution (sid), these problems have been fixed in version 1.4.18-1. We recommend that you upgrade your squirrelmail package.