The OpenID module in Drupal 6.x before 6.18, and the OpenID module 5.x before 5.x-1.4 for Drupal, violates the OpenID 2.0 protocol by not checking for reuse of openid.response_nonce values, which allows remote attackers to bypass authentication by leveraging an assertion from an OpenID provider.

The OpenID module in Drupal 6.x before 6.18, and the OpenID module 5.x before 5.x-1.4 for Drupal, violates the OpenID 2.0 protocol by not verifying the openid.return_to value, which allows remote attackers to bypass authentication by leveraging an assertion from an OpenID provider.

The OpenID module in Drupal 6.x before 6.18, and the OpenID module 5.x before 5.x-1.4 for Drupal, violates the OpenID 2.0 protocol by not ensuring that fields are signed, which allows remote attackers to bypass authentication by leveraging an assertion from an OpenID provider.

Cross-site scripting (XSS) vulnerability in OpenID 5.x before 5.x-1.2, a module for Drupal, allows remote attackers to inject arbitrary web script or HTML via unspecified vectors.

Cross-site request forgery (CSRF) vulnerability in OpenID 5.x before 5x.-1.2, a module for Drupal, allows remote attackers to hijack the authentication of unspecified victims to delete OpenID identities via unknown vectors.

The OpenID 5.x-1.0 and earlier module for Drupal does not properly verify the claimed_id returned by an OpenID provider, which allows remote OpenID providers to spoof OpenID authentication for domains associated with other providers.