High [CVE-2026-12383] ExternalEventStreamViewSet trusts Subject header without validation and leaks expected DN

A flaw was found in the Event-Driven Ansible (EDA) server. The ExternalEventStreamViewSet uses permissive access controls (permission_classes=[AllowAny], authentication_classes=[]) and relies solely on the Subject HTTP header value for mTLS authentication without verifying that the header originated from a trusted proxy.

Additionally, the expected certificate Distinguished Name is leaked in the 403 error response body. An attacker who can reach the EDA API endpoint with a spoofed Subject header can inject arbitrary events into mTLS-protected event streams, triggering downstream automation actions.

This flaw is a defense-in-depth failure in EDA that becomes exploitable when combined with the gateway header-forwarding issue (tracked as a separate CVE). The DN leak in the error response further reduces the difficulty of exploitation.

EDA has been included in AAP since version 2.4. The mTLS external event stream feature and the trust-of-Subject-header pattern apply to all EDA versions that support external event streams with mTLS authentication.

Red Hat severity: Important — CVSS 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N). Weakness: CWE-345.

Affected Red Hat products: Red Hat Ansible Automation Platform 2.5 for RHEL 8; Red Hat Ansible Automation Platform 2.5 for RHEL 9; Red Hat Ansible Automation Platform 2.6 for RHEL 9; Red Hat Ansible Automation Platform 2.7.