CVE-2021-32779 : Exploit Details and Defense Strategies

This article provides details about CVE-2021-32779, which involves an incorrect handling of URI '#fragment' element as part of the path element in Envoy.

Understanding CVE-2021-32779

CVE-2021-32779 relates to how Envoy, an open-source L7 proxy, mishandles URI fragments in specific versions.

What is CVE-2021-32779?

In affected versions of Envoy, a URI with a '#fragment' element is incorrectly processed as part of the path. This can lead to privilege escalation through specially crafted requests.

The Impact of CVE-2021-32779

The vulnerability affects versions of Envoy prior to 1.19.1, 1.18.4, 1.17.4, and 1.16.5. Exploitation could result in unauthorized access and escalation of privileges.

Technical Details of CVE-2021-32779

This section delves into the specific technical aspects of the vulnerability in Envoy.

Vulnerability Description

Envoy misinterprets '#fragment' elements in URIs, potentially allowing unauthorized access to protected resources.

Affected Systems and Versions

Versions of Envoy >= 1.16.0 and < 1.19.1 are impacted, with specific details outlined for each affected version.

Exploitation Mechanism

Exploiting this vulnerability involves sending a crafted URI with a '#fragment' element, exploiting Envoy's mishandling of such URIs.

Mitigation and Prevention

Learn how to mitigate the risks associated with CVE-2021-32779 and safeguard Envoy deployments.

Immediate Steps to Take

Update affected Envoy versions to 1.19.1, 1.18.4, 1.17.4, or 1.16.5 to address this vulnerability immediately.

Long-Term Security Practices

Implementing robust access controls and monitoring mechanisms can help prevent similar authorization bypass issues.

Patching and Updates

Regularly check for security updates and patches for Envoy to stay protected against known vulnerabilities.