The remote host is missing an update to hf announced via advisory DSA 1668-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%201668-1

Steve Kemp discovered that hf, an amateur-radio protocol suite using a soundcard as a modem, insecurely tried to execute an external command which could lead to the elevation of privileges for local users. For the stable distribution (etch), this problem has been fixed in version 0.7.3-4etch1. For the unstable distribution (sid), this problem has been fixed in version 0.8-8.1. We recommend that you upgrade your hf package.