OpenTTD is an open source clone of the simulation game "Transport Tycoon Deluxe" by Microprose.
Alexey Dobriyan discovered several format string vulnerabilities in OpenTTD.
A remote attacker could exploit these vulnerabilities to crash the OpenTTD server or client and possibly execute arbitrary code with the rights of the user running OpenTTD.
There are no known workarounds at this time.
All OpenTTD users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=games-simulation/openttd-0.4.0.1-r1"