The ruby-openid gem before 2.2.2 for Ruby allows remote OpenID providers to cause a denial of service (CPU consumption) via (1) a large XRDS document or (2) an XML Entity Expansion (XEE) attack.
CVSS 2.0MEDIUM 4.3·Network·No auth·Interaction —·EPSS 0.02132·Published 2013-12-12·Fixed in 2.2.2CWE-399