CVE-2021-32778 : Security Advisory and Response

An article detailing the CVE-2021-32778 vulnerability affecting Envoyproxy's Envoy versions.

Understanding CVE-2021-32778

This section provides an overview of the vulnerability and its impact.

What is CVE-2021-32778?

CVE-2021-32778 affects Envoyproxy's Envoy versions, leading to excessive CPU utilization when closing HTTP/2 streams.

The Impact of CVE-2021-32778

The vulnerability can be exploited to cause Denial of Service by clients opening and closing a large number of H/2 streams.

Technical Details of CVE-2021-32778

This section covers the technical aspects of the vulnerability.

Vulnerability Description

Envoy's procedure for resetting HTTP/2 streams has O(N^2) complexity, resulting in high CPU utilization with a large number of streams.

Affected Systems and Versions

Envoy versions 1.16.0 to 1.19.0 are affected, with specific version ranges for each affected release.

Exploitation Mechanism

Attackers can exploit this vulnerability by manipulating a large number of H/2 streams, leading to a DoS condition.

Mitigation and Prevention

Guidelines to mitigate the vulnerability and prevent potential exploitation.

Immediate Steps to Take

Limit the number of simultaneous HTTP/2 streams to mitigate the vulnerability. Deploy updated versions of Envoy containing fixes.

Long-Term Security Practices

Implement security measures to limit CPU utilization and prevent DoS attacks.

Patching and Updates

Ensure timely patching and updates of Envoyproxy's Envoy versions to address and prevent the CVE-2021-32778 vulnerability.