Smokescreen SSRF via deny list bypass (square brackets)

Medium5.3CVE-2022-29188 · Published May 10, 2022 · updated May 18, 2022

### Impact 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 surrounding the hostname with square brackets (e.g. `[example.com]`). ### Recommendation Upgrade Smokescreen to version 0.0.4 or later. ### Acknowledgements Thanks to [Axel Chong](https://github.com/haxatron) for reporting the issue. ### For more information Email us at security@stripe.com