WordPress Core - All known versions - Unauthenticated Blind Server Side Request Forgery

WordPress Core, in all known versions is vulnerable to blind Server-Side Request Forgery in its pingback feature. This is due to a Time-of-Check-Time-of-Use (TOC-TOU) race condition between validation checks and HTTP requests that makes it possible for URLs to be validated and then changed before being used by the software. This makes it possible for an attacker to change the domain in a pingback request to point to a different address than the one validated before, thus exposing hosts that should not be reachable on a server. The original researcher couldn't identify any ways to exploit this to take over vulnerable sites without other vulnerable services on the site meaning this would be difficult to exploit. The issue was first reported in 2017 and it's recommendd to block xmlrpc.php at the web server level, if not in use to prevent this from being exploited.

Requests carrying this pattern arrive without a session, so nothing upstream of the firewall gets a chance to reject them: WordSec's web application firewall inspects request payloads before WordPress loads them. No patched version is recorded yet, which is the case where a filtering layer matters most, because there is nothing to update to.

• Firewall
• Login Security
• Alerts