The install function in Firefox 1.0.3 allows remote web sites on the browser's whitelist, such as update.mozilla.org or addon.mozilla.org, to execute arbitrary Javascript with chrome privileges, leading to arbitrary code execution on the system when combined with vulnerabilities such as CVE-2005-1476, as demonstrated using a javascript: URL as the package icon and a cross-site scripting (XSS) attack on a vulnerable whitelist site.