Ory Polis, formerly known as BoxyHQ Jackson, bridges or proxies a SAML login flow to OAuth 2.0 or OpenID Connect. Versions prior to 26.2.0 contain a DOM-based Cross-Site Scripting (XSS) vulnerability in Ory Polis's login functionality. The application improperly trusts a URL parameter (callbackUrl), which is passed to router.push. An attacker can craft a malicious link that, when opened by an authenticated user (or an unauthenticated user that later logs in), performs a client-side redirect and executes arbitrary JavaScript in the context of their browser. This could lead to credential theft, internal network pivoting, and unauthorized actions performed on behalf of the victim. Version 26.2.0 contains a patch for the issue.