Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Contao is a powerful open source CMS that allows you to create professional websites and scalable web applications. Contao versions 4.13.0-RC1 through 4.13.2, it is possible to inject code into the canonical tag. As a workaround users may disable canonical tags in the root page settings.
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.