CVE-2021-32783 Information

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.

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:H

Reference

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

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

CHANGED

Integrity Impact

LOW

Availability Impact

NONE

Base Score

HIGH

Base Severity

8.5