CVE-2021-25746 Explained : Impact and Mitigation

A security issue was discovered in Kubernetes ingress-nginx that allows a user to obtain credentials of the ingress-nginx controller via .metadata.annotations in an Ingress object. This CVE poses a high severity risk with a CVSS base score of 7.6.

Understanding CVE-2021-25746

This CVE highlights a vulnerability in Kubernetes ingress-nginx that could lead to unauthorized access to cluster secrets through the controller credentials.

What is CVE-2021-25746?

The security issue in ingress-nginx enables a user to exploit .metadata.annotations in an Ingress object to access the controller's credentials, potentially compromising cluster secrets.

The Impact of CVE-2021-25746

With a high base severity score of 7.6, this vulnerability could result in unauthorized access to sensitive data and secrets within the Kubernetes cluster.

Technical Details of CVE-2021-25746

This section will cover detailed technical information regarding the vulnerability.

Vulnerability Description

The vulnerability allows a user to leverage annotations in an Ingress object to retrieve ingress-nginx controller credentials, potentially leading to unauthorized access to cluster secrets.

Affected Systems and Versions

Kubernetes ingress-nginx versions prior to 1.2.0 are affected by this security issue, making them vulnerable to exploitation.

Exploitation Mechanism

By manipulating .metadata.annotations in an Ingress object, threat actors can extract credentials of the ingress-nginx controller, granting them unauthorized access to cluster secrets.

Mitigation and Prevention

To secure your systems and prevent exploitation, follow these recommended mitigation steps:

Immediate Steps to Take

Update Kubernetes ingress-nginx to version 1.2.0 or above to eliminate the vulnerability.
Review and restrict access permissions for users creating or updating Ingress objects.

Long-Term Security Practices

Implement strict input validation to prevent unauthorized access via annotations.
Regularly monitor and audit Ingress object configurations for any suspicious changes.

Patching and Updates

Stay informed about security updates from Kubernetes and regularly apply patches to address known vulnerabilities.