socat is a multipurpose bidirectional relay, similar to netcat.
socat contains a syslog() based format string vulnerablility in the '_msg()' function of 'error.c'. Exploitation of this bug is only possible when socat is run with the '-ly' option, causing it to log messages to syslog.
Remote exploitation is possible when socat is used as a HTTP proxy client and connects to a malicious server. Local privilege escalation can be achieved when socat listens on a UNIX domain socket. Potential execution of arbitrary code with the privileges of the socat process is possible with both local and remote exploitations.
Disable logging to syslog by not using the '-ly' option when starting socat.
All socat users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-misc/socat-1.4.0.3"