CVE-2022-21656: Envoyproxy Envoy

Medium severity, CVSS 5.9. EPSS: 0.7% chance of exploitation in the next 30 days.

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

• Envoyproxy Envoy: before 1.20.2 (fixed in 1.20.2)

Published 2022-02-22. Last modified 2026-06-17.