Anubis accepts crafted redirect URLs in pass-challenge 'Try Again' buttons

Anubis is a Web AI Firewall Utility that weighs the soul of users' connections using one or more challenges in order to protect upstream resources from scraper bots. In versions 1.21.2 and below, attackers can craft malicious pass-challenge pages that cause a user to execute arbitrary JavaScript code or trigger other nonstandard schemes. An incomplete version of this fix was tagged at 1.21.2 and then the release process was aborted upon final testing. To work around this issue: block any requests to the /.within.website/x/cmd/anubis/api/pass-challenge route with the ?redir= parameter set to anything that doesn't start with the URL scheme http, https, or no scheme (local path redirect). This was fixed in version 1.21.3.