Multiple Cross-Site Scripting (XSS) issues were discovered in webpagetest 3.0. The vulnerabilities exist due to insufficient filtration of user-supplied data (benchmark, time) passed to the webpagetest-master/www/benchmarks/viewtest.php URL. An attacker could execute arbitrary HTML and script code in a browser in the context of the vulnerable website.
https://github.com/WPO-Foundation/webpagetest/issues/834
https://github.com/MarkLee131/awesome-web-pocs/blob/main/CVE-2017-6541.md