CVE-2023-27496: Envoyproxy Envoy

High severity, CVSS 7.5. EPSS: 0.8% chance of exploitation in the next 30 days.

Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9, the OAuth filter assumes that a `state` query param is present on any response that looks like an OAuth redirect response. Sending it a request with the URI path equivalent to the redirect path, without the `state` parameter, will lead to abnormal termination of Envoy process. Versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9 contain a patch. The issue can also be mitigated by locking down OAuth traffic, disabling the filter, or by filtering traffic before it reaches the OAuth filter (e.g. via a lua script).

Affected products

• Envoyproxy Envoy: before 1.22.9 (fixed in 1.22.9); from 1.23.0, before 1.23.6 (fixed in 1.23.6); from 1.24.0, before 1.24.4 (fixed in 1.24.4); from 1.25.0, before 1.25.3 (fixed in 1.25.3)

Published 2023-04-04. Last modified 2026-06-17.