The remote host is missing an update to pcal announced via advisory DSA 625-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20625-1

Danny Lungstrom discovered two buffer overflows in pcal, a program to generate Postscript calendars, that could lead to the execution of arbitrary code when compiling a calendar. For the stable distribution (woody) these problems have been fixed in version 4.7-8woody1. For the unstable distribution (sid) these problems have been fixed in version 4.8.0-1. We recommend that you upgrade your pcal package.