The remote host is missing an update to squirrelmail announced via advisory DSA 2091-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202091-1

SquirrelMail, a webmail application, does not employ a user-specific token for webforms. This allows a remote attacker to perform a Cross Site Request Forgery (CSRF) attack. The attacker may hijack the authentication of unspecified victims and send messages or change user preferences among other actions, by tricking the victim into following a link controled by the offender. In addition, a denial-of-service was fixed, which could be triggered when a passwords containing 8-bit characters was used to log in (CVE-2010-2813). For the stable distribution (lenny), these problems have been fixed in version 1.4.15-4+lenny3.1. For the testing distribution (squeeze) and the unstable distribution (sid), these problems have been fixed in version 1.4.21-1. We recommend that you upgrade your squirrelmail packages.