The XML-RPC flaw was discovered by James Bercegay of GulfTech Security Research. Bercegay found that the libraries are “vulnerable to a very high risk remote php code execution vulnerability that may allow for an attacker to compromise a vulnerable webserver … By creating an XML file that uses single quotes to escape into the eval() call an attacker can easily execute php code on the target server.”
Updated copies of the libraries are now available, and immediate upgrades are recommended. The nature of the flaw poses a dilemma for site operators on shared hosting services, who may run affected applications on their sites but not have the ability to update the server’s PHP installation with the secure libraries. Disabling XML-RPC features is the recommended workaround.