Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
The Contact Form Check Tester WordPress plugin through 1.0.2 settings are visible to all registered users in the dashboard and are lacking any sanitisation. As a result, any registered user, such as subscriber, can leave an XSS payload in the plugin settings, which will be triggered by any user visiting them, and could allow for privilege escalation. The vendor decided to close the plugin.
CWE-79 - Cross Site Scripting
Cross-Site Scripting, commonly referred to as XSS, is the most dominant class of vulnerabilities. It allows an attacker to inject malicious code into a pregnable web application and victimize its users. The exploitation of such a weakness can cause severe issues such as account takeover, and sensitive data exfiltration. Because of the prevalence of XSS vulnerabilities and their high rate of exploitation, it has remained in the OWASP top 10 vulnerabilities for years.