Multiple cross-site scripting (XSS) vulnerabilities in Bugzilla 2.18.x before 2.18.6, 2.20.x before 2.20.3, 2.22.x before 2.22.1, and 2.23.x before 2.23.3 allow remote authenticated users to inject arbitrary web script or HTML via (1) page headers using the H1, H2, and H3 HTML tags in global/header.html.tmpl, (2) description fields of certain items in various edit cgi scripts, and (3) the id parameter in showdependencygraph.cgi.