Captcha Protect is a Traefik middleware to add an anti-bot challenge to individual IPs in a subnet when traffic spikes are detected from that subnet. Prior to version 1.12.2, a reflected cross-site scripting (XSS) vulnerability exists in github.com/libops/captcha-protect. The challenge page accepted a client-supplied destination value and rendered it into HTML using Go's text/template. Because text/template does not perform contextual HTML escaping, an attacker could supply a crafted destination value that breaks out of the hidden input attribute and injects arbitrary script into the challenge page. This issue has been patched in version 1.12.2.
https://github.com/libops/captcha-protect/security/advisories/GHSA-ph62-4j5g-2q4r
https://github.com/libops/captcha-protect/releases/tag/v1.12.2
https://github.com/libops/captcha-protect/commit/eef6211ecd1147273be484d913b81c68c0bd8d3f