Copyright © 2012 Red Hat, Inc. All rights reserved. Important 2026-07-28T12:00:00 openshift/oauth-proxy: openshift/oauth-proxy: underscore header smuggling enables identity impersonation on WSGI/PHP upstreams 8.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N CWE-436

A flaw was found in openshift/oauth-proxy. The proxy sets authenticated identity headers using only dash-variant keys (X-Forwarded-User) but does not strip underscore-variant keys (X_Forwarded_User) from incoming requests. WSGI and PHP frameworks normalize both variants to the same variable, allowing an authenticated low-privilege user to smuggle a forged identity that may override the legitimate authenticated identity in the upstream application.

A flaw was found in openshift/oauth-proxy. The proxy sets authenticated identity headers using only dash-variant keys (X-Forwarded-User) but does not strip underscore-variant keys (X_Forwarded_User) from incoming requests. WSGI and PHP frameworks normalize both variants to the same variable, allowing an authenticated low-privilege user to smuggle a forged identity that may override the legitimate authenticated identity in the upstream application.

This issue was discovered by Jeremy Choi (Red Hat). Upstream application hardening: validate X-Forwarded-User against the expected session identity. Reject requests where identity headers do not match the authenticated session. Red Hat OpenShift Container Platform 4 Affected openshift4/ose-oauth-proxy Red Hat OpenShift Container Platform 4 Affected openshift4/ose-oauth-proxy-rhel9 https://www.cve.org/CVERecord?id=CVE-2026-49332 https://nvd.nist.gov/vuln/detail/CVE-2026-49332