CVE-2020-8555 : What You Need to Know

Kubernetes kube-controller-manager SSRF vulnerability allows leaking arbitrary information from unprotected endpoints within the master's host network.

Understanding CVE-2020-8555

The vulnerability affects Kubernetes versions v1.0-1.14, prior to v1.15.12, v1.16.9, v1.17.5, and v1.18.0, potentially leading to Server Side Request Forgery (SSRF) attacks.

What is CVE-2020-8555?

The Kubernetes kube-controller-manager in various versions is susceptible to SSRF, enabling authorized users to extract up to 500 bytes of data from vulnerable endpoints.

The Impact of CVE-2020-8555

CVSS Base Score: 6.3 (Medium Severity)
Attack Vector: Network
Confidentiality Impact: High
Attack Complexity: High
Privileges Required: Low
Scope: Changed

Technical Details of CVE-2020-8555

The following technical aspects are associated with this vulnerability:

Vulnerability Description

The vulnerability allows certain authorized users to leak up to 500 bytes of arbitrary information from unprotected endpoints within the master's host network.

Affected Systems and Versions

Kubernetes versions v1.0-1.14
Versions prior to v1.15.12, v1.16.9, v1.17.5
Version v1.18.0

Exploitation Mechanism

The vulnerability can be exploited by certain authorized users to extract data from vulnerable endpoints within the master's host network.

Mitigation and Prevention

To address CVE-2020-8555, consider the following steps:

Immediate Steps to Take

Add endpoint protections on the master
Restrict usage of vulnerable volume types
Constrain usage with a PodSecurityPolicy or third-party admission controller
Restrict StorageClass write permissions through RBAC

Long-Term Security Practices

Regularly update Kubernetes to patched versions
Implement network segmentation to limit unauthorized access
Conduct security audits and penetration testing

Patching and Updates

Upgrade Kubernetes to versions that address the SSRF vulnerability
Stay informed about security advisories and apply patches promptly