From bleepingcomputer.com
Admins and owners of WordPress websites are urged to immediately apply the Jetpack 7.9.1 critical security update to prevent potential attacks that could abuse a vulnerability that has existed since Jetpack 5.1.
You can update your installation to the 7.9.1 version through your dashboard, or manually download the Jetpack 7.9.1 release here.
Jetpack is an extremely popular WordPress plugin that provides free security, performance, and site management features including site backups, secure logins, malware scanning, and brute-force attack protection.