Security researcher Nir Goldshlager has identified vulnerabilities in widely-used WordPress and Drupal that enable XML denial-of-service (DoS) attacks.
Updating to WordPress 3.9.2 and to Drupal core 7.31 or 6.33 will mitigate the issues.
The WordPress issue exists in PHP's XML processing, according to a post on the WordPress website, which adds that updating protects against certain brute force attacks and also addresses possible code execution vulnerabilities.
Drupal is affected because the PHP XML Parser used by a publicly available XML-RPC endpoint is vulnerable to an XML entity expansion attack, according to a post on the Drupal website.
Removing the xmlrpc.php file from the root of Drupal core and disabling the OpenID module will also mitigate the issue, according to the post.