JanRain PHP OpenID library (aka php-openid) 2.2.2 allows remote attackers to obtain sensitive information via a direct request to a .php file, which reveals the installation path in an error message, as demonstrated by Auth/Yadis/Yadis.php and certain other files.

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.

PHP remote file inclusion vulnerability in includes/openid/Auth/OpenID/BBStore.php in phpBB Openid 0.2.0 allows remote attackers to execute arbitrary PHP code via a URL in the openid_root_path parameter.

Cross-site request forgery (CSRF) vulnerability in OpenID allows remote attackers to restore the login session of a user on an OpenID enabled site via unspecified vectors related to an arbitrary remote web site and cached tokens, after the user has signed into an OpenID server, logged into the OpenID enabled site, and then logged out of the OpenID enabled site.

OpenID allows remote attackers to forcibly log a user into an OpenID enabled site, divulge the user's personal information to this site, and add it site to the trusted sites list via a crafted web page, related to cached tokens.