The remote host is missing an update as announced via advisory SSA:2004-140-01.

https://secure1.securityspace.com/smysecure/catid.html?in=SSA:2004-140-01

New cvs packages are available for Slackware 8.1, 9.0, 9.1, and -current to fix a buffer overflow vulnerability which could allow an attacker to run arbitrary programs on the CVS server. Sites running a CVS server should upgrade to the new CVS package right away. More details about this issue may be found in the Common Vulnerabilities and Exposures (CVE) database: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2004-0396