wabac.js provides a full web archive replay system, or 'wayback machine', using Service Workers. A Reflected Cross-Site Scripting (XSS) vulnerability exists in the 404 error handling logic of wabac.js v2.23.10 and below. The parameter `requestURL` (derived from the original request target) is directly embedded into an inline `<script>` block without sanitization or escaping. This allows an attacker to craft a malicious URL that executes arbitrary JavaScript in the victim’s browser. The scope may be limited by CORS policies, depending on the situation in which wabac.js is used. The vulnerability is fixed in wabac.js v2.23.11.

Webrecorder packages are vulnerable to XSS through 404 error handling logic