n8n allows open redirects via the /signin endpoint

n8n is a workflow automation platform. Versions prior to 1.98.0 have an Open Redirect vulnerability in the login flow. Authenticated users can be redirected to untrusted, attacker-controlled domains after logging in, by crafting malicious URLs with a misleading redirect query parameter. This may lead to phishing attacks by impersonating the n8n UI on lookalike domains (e.g., n8n.local.evil.com), credential or 2FA theft if users are tricked into re-entering sensitive information, and/or reputation risk due to the visual similarity between attacker-controlled domains and trusted ones. The vulnerability affects anyone hosting n8n and exposing the `/signin` endpoint to users. The issue has been patched in version 1.98.0. All users should upgrade to this version or later. The fix introduces strict origin validation for redirect URLs, ensuring only same-origin or relative paths are allowed after login.