CVE-2018-16886 Explained : Impact and Mitigation

CVE-2018-16886, published on January 14, 2019, affects versions of etcd prior to 3.2.26 and 3.3.11. This vulnerability is related to authentication when using role-based access control (RBAC) and enabling client certificate authentication.

Understanding CVE-2018-16886

This CVE highlights a security vulnerability in etcd versions 3.2.x before 3.2.26 and 3.3.x before 3.3.11.

What is CVE-2018-16886?

Versions of etcd prior to 3.2.26 and 3.3.11 have an authentication vulnerability when using RBAC and client certificate authentication. It allows a remote attacker to authenticate as a valid RBAC user by exploiting a TLS certificate issue.

The Impact of CVE-2018-16886

CVSS Score: 6.8 (Medium)
Attack Vector: Network
Confidentiality Impact: High
Integrity Impact: High
Privileges Required: Low

Technical Details of CVE-2018-16886

This section provides more in-depth technical insights into the vulnerability.

Vulnerability Description

The vulnerability allows a remote attacker to impersonate a valid RBAC user by exploiting a TLS certificate issue in the etcd server.

Affected Systems and Versions

Product: etcd
Vendor: The etcd Project
Vulnerable Versions: 3.2.x before 3.2.26 and 3.3.x before 3.3.11

Exploitation Mechanism

The attacker can authenticate as a valid RBAC user by using any trusted client certificate in a REST API request to the gRPC-gateway if the CN in the etcd client server TLS certificate matches the RBAC username.

Mitigation and Prevention

It is crucial to take immediate steps to address and prevent the exploitation of this vulnerability.

Immediate Steps to Take

Update etcd to versions 3.2.26 or 3.3.11 to mitigate the vulnerability.
Review and adjust RBAC and client certificate authentication configurations.

Long-Term Security Practices

Regularly review and update TLS certificates and configurations.
Implement strong authentication mechanisms and access controls.

Patching and Updates

Apply security patches provided by the vendor promptly.