CVE-2019-18802: Envoyproxy Envoy

Critical severity, CVSS 9.8. EPSS: 2.5% chance of exploitation in the next 30 days.

An issue was discovered in Envoy 1.12.0. An untrusted remote client may send an HTTP header (such as Host) with whitespace after the header content. Envoy will treat "header-value " as a different string from "header-value" so for example with the Host header "example.com " one could bypass "example.com" matchers.

Affected products

• Envoyproxy Envoy: up to and including 1.12.1

Published 2019-12-13. Last modified 2026-06-17.