Describe the bug
I've been attempting to use a third party IdP to act as a source for my Authentik server via SAML.
Using SAML tracer I've been able to verify successful flow from authentik, to the third party sign-on, but on the final SAML post to authentik, a 405 Error is returned.

To Reproduce
Steps to reproduce the behavior:

1. Set up SAML Source with correct SSO URL, Verification Cert, and Redirect Binding
2. Add the source to a stage in default auth flow
3. Attempt to log into the service via third party IdP
4. After successful authentication, the final SAML POST submission with base64 encoded data fails with a 405 Error

Expected behavior
Authentik shouldn't return a 405 Error, since the SAML protocol should expect a POST request.

Authentik Logs on the 405 Response:

Logs
Output of docker-compose logs or kubectl logs respectively

Version and Deployment (please complete the following information):

• authentik version: . 2025.6.3
• Deployment: docker-compose (behind traefik reverse proxy)

Additional context
Add any other context about the problem here.