The remote host is missing an update as announced via advisory SSA:2004-207-02.

https://secure1.securityspace.com/smysecure/catid.html?in=SSA:2004-207-02

New mod_ssl packages are available for Slackware 8.1, 9.0, 9.1, 10.0 and -current to fix a security issue. A format string vulnerability in mod_proxy hook functions could allow an attacker to run code as the mod_ssl user. Sites using mod_ssl should upgrade (be sure to back up your existing key files first).