CVE-2022-21656

Name: CVE-2022-21656
Creator: NVD / NIST
Published: 2022-02-22T23:15:11.223+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.9/10EPSS 0.77%

Last modified Jun 17, 2026

CVE-2022-21656 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. Envoy is an open source edge and service proxy, designed for cloud-native applications. The default_validator.cc implementation used to implement the default certificate validation routines has a "type confusion" bug when processing subjectAltNames. EPSS estimates a 0.77% chance of exploitation in the next 30 days.

Description

Envoy is an open source edge and service proxy, designed for cloud-native applications. The default_validator.cc implementation used to implement the default certificate validation routines has a "type confusion" bug when processing subjectAltNames. This processing allows, for example, an rfc822Name or uniformResourceIndicator to be authenticated as a domain name. This confusion allows for the bypassing of nameConstraints, as processed by the underlying OpenSSL/BoringSSL implementation, exposing the possibility of impersonation of arbitrary servers. As a result Envoy will trust upstream certificates that should not be trusted.

Metrics

CVSS 3.1

5.9/10

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS Probability

0.77%

50.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Envoyproxy	Envoy	< 1.20.2

References

https://github.com/envoyproxy/envoy/commit/bb95af848c939cfe5b5ee33c5b1770558077e64ePatch, Third Party Advisory
https://github.com/envoyproxy/envoy/security/advisories/GHSA-c9g7-xwcv-pjx2Issue Tracking, Third Party Advisory
https://github.com/envoyproxy/envoy/commit/bb95af848c939cfe5b5ee33c5b1770558077e64ePatch, Third Party Advisory
https://github.com/envoyproxy/envoy/security/advisories/GHSA-c9g7-xwcv-pjx2Issue Tracking, Third Party Advisory

Timeline

Published: Feb 22, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2022-21656?

How severe is CVE-2022-21656?

CVE-2022-21656 has a CVSS score of 5.9/10 (MEDIUM severity). The EPSS model estimates a 0.77% probability of exploitation in the next 30 days.

How do I fix CVE-2022-21656?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2022-21656?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST