Smokescreen is a simple HTTP proxy that fogs over naughty URLs. The primary use case for Smokescreen is to prevent server-side request forgery (SSRF) attacks in which external attackers leverage the behavior of applications to connect to or scan internal infrastructure. Smokescreen also offers an option to deny access to additional (e.g., external) URLs by way of a deny list. There was an issue in Smokescreen that made it possible to bypass the deny list feature by appending a dot to the end of user-supplied URLs, or by providing input in a different letter case. Recommended to upgrade Smokescreen to version 0.0.3 or later.

Smokescreen SSRF via deny list bypass