Header dropping in traefik
ImpactThere exists a potential header vulnerability in Traefik's handling of the Connection header. Active exploitation of this issue is unlikely, as it requires that a removed header would lead to a privilege escalation, however, the Traefik team has addressed this issue to prevent any potential abuse.DetailsIf you have a chain of Traefik middlewares, and one of them sets a request header `Important-Security-Header`, then sending a request with the following Connection header will cause it to be removed before the request was sent:In this case, the backend does not see the request header `Important-Security-Header`.PatchesTraefik v2.4.x: https://github.com/traefik/traefik/releases/tag/v2.4.13WorkaroundsNo.For more informationIf you have any questions or comments about this advisory, [open an issue](https://github.com/traefik/traefik/issues).