CVE-2021-32783 : Security Advisory and Response
Learn about CVE-2021-32783, an authorization bypass vulnerability in Contour before 1.17.1, allowing unauthorized access to Envoy's admin interface. Find out the impact, affected systems, exploitation mechanism, and mitigation steps.
Contour, a Kubernetes ingress controller using Envoy proxy, before version 1.17.1 is vulnerable to an authorization bypass issue that allows a specially crafted ExternalName type Service to access Envoy's admin interface. This may lead to a denial of service attack or expose sensitive information such as TLS KeyPairs.
Understanding CVE-2021-32783
This CVE discloses an authorization bypass vulnerability in Contour, affecting versions prior to 1.17.1.
What is CVE-2021-32783?
CVE-2021-32783 describes an authorization bypass issue in Contour that enables unauthorized access to Envoy's admin interface, potentially leading to service disruption or exposure of sensitive data stored in Envoy's configuration.
The Impact of CVE-2021-32783
The impact of this vulnerability is rated as HIGH based on CVSS v3.1 metrics due to the potential for a denial of service and exposure of sensitive information. The attack complexity is low, and the availability impact is high.
Technical Details of CVE-2021-32783
CVE-2021-32783 has the following technical details:
Vulnerability Description
The vulnerability allows access to Envoy's admin interface via a specially crafted ExternalName Service, potentially leading to denial of service or exposure of sensitive information.
Affected Systems and Versions
Contour versions prior to 1.17.1 are affected by this vulnerability.
Exploitation Mechanism
By abusing the ExternalName type Service, an attacker can access Envoy's admin interface, bypassing Contour's limitations.
Mitigation and Prevention
To mitigate the risks associated with CVE-2021-32783, consider the following steps:
Immediate Steps to Take
- Upgrade Contour to version 1.17.1 or later to address the vulnerability.
- Monitor network traffic for any suspicious access to Envoy's admin interface.
Long-Term Security Practices
- Regularly update and patch Contour and its dependencies to prevent security vulnerabilities.
- Implement network security measures to restrict access to sensitive interfaces.
Patching and Updates
Apply security patches released by Contour promptly to protect against known vulnerabilities.