The FV Flowplayer Video Player WordPress plugin is vulnerable to Reflected Cross-Site Scripting via the player_id parameter found in the ~/view/stats.php file which allows attackers to inject arbitrary web scripts in versions 7.5.0.727 - 7.5.2.727.
View the template here CVE-2021-39350.yaml
References:
https://www.wordfence.com/vulnerability-advisories/#CVE-2021-39350