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OpenAdvisories
High · 7.4 CVE-2022-21656 EUVD-2022-26874

X.509 subjectAltName matching bypass in Envoy

Published Feb 22, 2022 · Updated Apr 23, 2025 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
envoyproxy envoy < 1.20.2 —

References