CVE-2020-11653 : Security Advisory and Response

An issue was discovered in Varnish Cache before 6.0.6 LTS, 6.1.x and 6.2.x before 6.2.3, and 6.3.x before 6.3.2. It occurs when communication with a TLS termination proxy uses PROXY version 2. There can be an assertion failure and daemon restart, which causes a performance loss.

Understanding CVE-2020-11653

This CVE identifies a vulnerability in Varnish Cache that can lead to an assertion failure and daemon restart when communicating with a TLS termination proxy using PROXY version 2.

What is CVE-2020-11653?

The CVE-2020-11653 vulnerability is a specific issue found in Varnish Cache versions prior to 6.0.6 LTS, 6.1.x, 6.2.x, and 6.3.x. It stems from the interaction with a TLS termination proxy using PROXY version 2, resulting in potential performance degradation.

The Impact of CVE-2020-11653

The vulnerability can lead to an assertion failure and subsequent daemon restart, causing performance issues and potential service disruptions for systems utilizing Varnish Cache.

Technical Details of CVE-2020-11653

Vulnerability Description The issue arises in Varnish Cache versions before 6.0.6 LTS, 6.1.x, 6.2.x, and 6.3.x when communicating with a TLS termination proxy using PROXY version 2, leading to an assertion failure and daemon restart.

Affected Systems and Versions

Vendor: n/a
Product: n/a
Versions: All versions are affected

Exploitation Mechanism The vulnerability is exploited when communication occurs with a TLS termination proxy utilizing PROXY version 2, triggering the assertion failure and subsequent daemon restart.

Mitigation and Prevention

Immediate Steps to Take

Update Varnish Cache to version 6.0.6 LTS, 6.1.x, 6.2.3, or 6.3.2 to mitigate the vulnerability.
Monitor for any unusual performance degradation that could indicate exploitation of the issue.

Long-Term Security Practices

Regularly update and patch Varnish Cache to the latest versions to address known vulnerabilities.
Implement network security measures to prevent unauthorized access to systems.

Patching and Updates Ensure timely application of security patches and updates provided by Varnish Cache to address vulnerabilities and enhance system security.