The remote host is missing an update to hsftp announced via advisory DSA 447-1.

https://secure1.securityspace.com/smysecure/catid.html?in=DSA%20447-1

During an audit, Ulf Harnhammar discovered a format string vulnerability in hsftp. This vulnerability could be exploited by an attacker able to create files on a remote server with carefully crafted names, to which a user would connect using hsftp. When the user requests a directory listing, particular bytes in memory could be overwritten, potentially allowing arbitrary code to be executed with the privileges of the user invoking hsftp. Note that while hsftp is installed setuid root, it only uses these privileges to acquire locked memory, and then relinquishes them. For the current stable distribution (woody) this problem has been fixed in version 1.11-1woody1. For the unstable distribution (sid), this problem will be fixed soon. We recommend that you update your hsftp package.