The remote host is missing an update to libapache-mod-security announced via advisory DSA 2506-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%202506-1

Qualys Vulnerability & Malware Research Labs discovered a vulnerability in ModSecurity, a security module for the Apache webserver. In situations where both 'Content:Disposition: attachment' and 'Content-Type: multipart' were present in HTTP headers, the vulernability could allow an attacker to bypass policy and execute cross-site script (XSS) attacks through properly crafted HTML documents. For the stable distribution (squeeze), this problem has been fixed in version 2.5.12-1+squeeze1. For the testing distribution (wheezy), this problem has been fixed in version 2.6.6-1. For the unstable distribution (sid), this problem has been fixed in version 2.6.6-1. In testing and unstable distribution, the source package has been renamed to modsecurity-apache. We recommend that you upgrade your libapache-mod-security packages.