CVE-2021-32780 : What You Need to Know

This article provides an overview of CVE-2021-32780, highlighting the vulnerability in the Envoy proxy affecting versions 1.19.0 and 1.18.0.

Understanding CVE-2021-32780

CVE-2021-32780 involves the incorrect handling of H/2 GOAWAY followed by SETTINGS frames in Envoy proxy versions, leading to Denial of Service due to an invalid state transition.

What is CVE-2021-32780?

In affected versions of Envoy, the proxy improperly transitions a connection state, resulting in abnormal termination of the process when specific frames are received in a sequence, causing a DoS vulnerability.

The Impact of CVE-2021-32780

The vulnerability poses a high risk with a CVSS base score of 8.6, allowing untrusted upstream servers to exploit the issue and disrupt services.

Technical Details of CVE-2021-32780

This section delves into the specific technical aspects of the CVE, including the vulnerability description, affected systems, and the exploitation mechanism.

Vulnerability Description

Envoy incorrectly transitions connection states upon receiving certain frames, leading to the termination of the process and potential DoS attacks by malicious actors.

Affected Systems and Versions

The vulnerability impacts Envoy versions >= 1.19.0 and < 1.19.1, as well as >= 1.18.0 and < 1.18.4, exposing systems using these versions to exploitation.

Exploitation Mechanism

By delivering a sequence of H/2 frames, untrusted upstream servers can trigger abnormal state transitions in Envoy, resulting in Denial of Service scenarios.

Mitigation and Prevention

To address CVE-2021-32780, immediate steps, long-term security practices, and the importance of patching and updates are crucial.

Immediate Steps to Take

Users should update Envoy to versions 1.19.1 or 1.18.4 that contain fixes to prevent processing of H/2 frames after a connection transitions to the CLOSED state.

Long-Term Security Practices

Implementing proper input validation, monitoring network traffic, and maintaining updated software are essential to prevent similar vulnerabilities in the future.

Patching and Updates

Regularly checking for security advisories and promptly applying patches released by Envoyproxy is vital to protect systems from known vulnerabilities.