ruby1.8, ruby1.9.1, ruby2.0, ruby2.1 vulnerabilities

Will Wood discovered that Ruby incorrectly handled the encodes() function.
An attacker could possibly use this issue to cause Ruby to crash, resulting
in a denial of service, or possibly execute arbitrary code. The default
compiler options for affected releases should reduce the vulnerability to a
denial of service. (CVE-2014-4975)

Willis Vandevanter discovered that Ruby incorrectly handled XML entity
expansion. An attacker could use this flaw to cause Ruby to consume large
amounts of resources, resulting in a denial of service. (CVE-2014-8080)