LibYAML is a YAML 1.1 parser and emitter written in C.
A heap-based buffer overflow flaw was found in the way libyaml parsed YAML tags.
A remote attacker could provide a specially-crafted YAML document which when parsed by LibYAML, would cause the application to crash or, potentially, execute arbitrary code with the privileges the user who is running the application.
There is no known workaround at this time.
All LibYAML users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=dev-libs/libyaml-0.1.5"