WordPress admins are being warned to remove a buggy plugin or risk a total site takeover.
This particular threat relates to a plugin which is no longer in use: Modern WPBakery page builder addons. The vulnerability in the plugin, known as CVE-2021-24284, allows "unauthenticated arbitrary file upload via the 'uploadFontIcon' AJAX action". This means that attackers could upload rogue PHP files to the WordPress site, leading to remote code execution and a complete site takeover.
Roughly 1.6 million sites have been scanned to check for the plugin's presence by bad actors, and current estimates suggest somewhere in the region of 4,000 to 8,000 websites are still playing host to the plugin.
Check and remove ASAP
The current advice is to check for the plugin, and then remove it as soon as you possibly can. It's been completely abandoned, and no security-related fixes will be forthcoming.
If you have it installed, you're on your own, and it's likely only a matter of time before the exploiters make their way to your Modern WPBakery hosting website and start getting up to mischief.
Do yourself and your site visitors a favour: Remove this outdated invitation to site-wide compromise as soon as you possibly can.