The remote host is missing an update to acm announced via advisory DSA 333-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20333-1

acm, a multi-player aerial combat simulation, uses a network protocol based on the same RPC implementation used in many C libraries. This implementation was found to contain an integer overflow vulnerability which could be exploited to execute arbitrary code. For the stable distribution (woody) this problem has been fixed in version 5.0-3.woody.1. For the unstable distribution (sid) this problem has been fixed in version 5.0-10. We recommend that you update your acm package.