Description
WordPress Plugin Smush Image Compression and Optimization is prone to multiple vulnerabilities, including cross-site scripting and PHP object injection vulnerabilities. Exploiting these issues could allow an attacker to execute arbitrary script code in the browser of an unsuspecting user in the context of the affected site, allowing the attacker to steal cookie-based authentication credentials and launch other attacks, or to possibly execute arbitrary PHP code within the context of the affected webserver process. WordPress Plugin Smush Image Compression and Optimization version 2.9.1 is vulnerable; prior versions may also be affected.
Remediation
Update to plugin version 3.0.1 or latest
References
https://www.ripstech.com/php-security-calendar-2018/#day-8
https://plugins.svn.wordpress.org/wp-smushit/trunk/readme.txt