proxytunnel -- format string vulnerability

A Gentoo Linux Security Advisory reports:

Florian Schilhabel of the Gentoo Linux Security Audit
project found a format string vulnerability in
Proxytunnel. When the program is started in daemon mode
(-a [port]), it improperly logs invalid proxy answers to
syslog.
A malicious remote server could send specially-crafted
invalid answers to exploit the format string
vulnerability, potentially allowing the execution of
arbitrary code on the tunnelling host with the rights of
the Proxytunnel process.