via wptavern.com => original post link
WPScan is reporting a hacking campaign actively exploiting an unpatched vulnerability in the Ultimate Member plugin, which allows unauthenticated attackers to create new user accounts with administrative privileges and take over the site. The vulnerability has been assigned a CVSSv3.1 (Common Vulnerability Scoring System) score of 9.8 (Critical).
Automattic’s WP.cloud and Pressable.com hosting platforms picked up on a trend in compromised sites where each had rogue new administrators popping up. After further investigation they found a discussion on the WordPress.org support forums about a potential Privilege Escalation vulnerability in the plugin, as well as indications that it was already being actively exploited.
Ultimate Member, which is active on more than 200,000 WordPress sites, patched the plugin, but WPScan reports that it wasn’t sufficient.