CVE-2021-39204 : Exploit Details and Defense Strategies

Pomerium is an open-source identity-aware access proxy that experienced a vulnerability resulting in excessive CPU usage.

Understanding CVE-2021-39204

This CVE details the specific vulnerability in Pomerium related to CPU utilization.

What is CVE-2021-39204?

Pomerium, based on Envoy, mishandles the resetting of HTTP/2 streams, leading to high CPU usage and potential denial of service (DoS) conditions.

The Impact of CVE-2021-39204

The vulnerability has a CVSS base score of 7.5 (High) with a HIGH impact on availability.

Technical Details of CVE-2021-39204

Details regarding the vulnerability, affected systems, and exploitation.

Vulnerability Description

The issue arises from Envoy incorrectly managing stream resets, causing CPU spikes and possible DoS situations.

Affected Systems and Versions

Affected product: Pomerium
Versions prone to issue: < 0.14.8, >= 0.15.0, < 0.15.1

Exploitation Mechanism

Exploiting this vulnerability involves triggering a large number of HTTP/2 stream resets within Pomerium.

Mitigation and Prevention

Steps to mitigate the risk and prevent further exploitation of the vulnerability.

Immediate Steps to Take

Update Pomerium to versions 0.14.8 and 0.15.1, which have the vulnerability patched.
Monitor CPU usage for any unusual spikes.

Long-Term Security Practices

Regularly update Pomerium and its dependencies.
Employ network-level protections against DoS attacks.

Patching and Updates

Stay informed about security advisories and patches from Pomerium and related projects.