WordPress websites were under attack due to vulnerability in a popular WP plugin since March 15, 2019.
Vulnerable component: Easy WP SMTP
CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C
CWE-ID: CWE-502 - Deserialization of Untrusted Data
The vulnerability allows a remote attacker to compromise vulnerable website.
The vulnerability exists due to insecure input validation when processing serialized data passed via the "swpsmtp_import_settings" HTTP POST parameter to /easy-wp-smtp.php script. A remote unauthenticated attacker can import arbitrary wp_options and reconfigure WordPress to allow user registration with administrative privileges.
Successful exploitation of this vulnerability may result in complete compromise of vulnerable website.
Note: this vulnerability is being actively exploited in the wild.