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CVE-2021-32777

8.6 · HIGH

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures.

Published Aug 24, 2021CWE-551EPSS 3.33%

Overview

CVE-2021-32777 is a high-severity vulnerability. It was published on August 24, 2021 and has a CVSS 3.1 base score of 8.6 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions when ext-authz extension is sending request headers to the external authorization service it must merge multiple value headers according to the HTTP spec. However, only the last header value is sent. This may allow specifically crafted requests to bypass authorization. Attackers may be able to escalate privileges when using ext-authz extension or back end service that uses multiple value headers for authorization. A specifically constructed request may be delivered by an untrusted downstream peer in the presence of ext-authz extension. Envoy versions 1.19.1, 1.18.4, 1.17.4, 1.16.5 contain fixes to the ext-authz extension to correctly merge multiple request header values, when sending request for authorization.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/envoyproxy/envoy/security/advisories/GHSA-6g4j-5vrw-2m8hRefwww.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_historyGitHubgithub.com/envoyproxy/envoy/security/advisories/GHSA-6g4j-5vrw-2m8hRefwww.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_history

How CyberStrike helps

Frequently asked questions

What is CVE-2021-32777?

CVE-2021-32777 is a high-severity vulnerability. It was published on August 24, 2021 and has a CVSS 3.1 base score of 8.6 (HIGH).

How severe is CVE-2021-32777?

This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-32777?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-32777?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-32777 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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