Spring Framework (versions 5.0.x prior to 5.0.7, versions 4.3.x prior to 4.3.18, and older unsupported versions) allow web applications to change the HTTP request method to any HTTP method (including TRACE) using the HiddenHttpMethodFilter in Spring MVC. If an application has a pre-existing XSS vulnerability, a malicious user (or attacker) can use this filter to escalate to an XST (Cross Site Tracing) attack.