Net::Server is an extensible, generic Perl server engine. It is used by several Perl applications like Postgrey.
The log function of Net::Server does not handle format string specifiers properly before they are sent to syslog.
By sending a specially crafted datastream to an application using Net::Server, an attacker could cause a Denial of Service.
There is no known workaround at this time.
All Net::Server should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=dev-perl/net-server-0.88"