Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Jenkins 2.196 and earlier, LTS 2.176.3 and earlier did not escape the reason why a queue items is blcoked in tooltips, resulting in a stored XSS vulnerability exploitable by users able to control parts of the reason a queue item is blocked, such as label expressions not matching any idle executors.
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.