Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
In Jenkins 2.321 through 2.355 (both inclusive) and LTS 2.332.1 through LTS 2.332.3 (both inclusive) the HTML output generated for new symbol-based SVG icons includes the 'title' attribute of 'l:ionicon' (until Jenkins 2.334) and 'alt' attribute of 'l:icon' (since Jenkins 2.335) without further escaping, resulting in a cross-site scripting (XSS) vulnerability.
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.