The remote host is missing an update to courier-authlib announced via advisory DSA 1688-2.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201688-2

The update of courier-authlib in DSA 1688-1 caused a regression with setups that do not use mail addresses for authentification. This update fixes this regression. For reference, the full advisory text is below. Two SQL injection vulnerabilities have beein found in courier-authlib, the courier authentification library. The MySQL database interface used insufficient escaping mechanisms when constructing SQL statements, leading to SQL injection vulnerabilities if certain charsets are used (CVE-2008-2380). A similar issue affects the PostgreSQL database interface (CVE-2008-2667). For the stable distribution (etch), these problems have been fixed in version 0.58-4+etch3. For the testing distribution (lenny) and the unstable distribution (sid), these problems have been fixed in version 0.61.0-1+lenny1. We recommend that you upgrade your courier-authlib packages.