This vulnerability arises because the email backend of the automation-controller passes user-supplied SMTP host and port parameters directly to the SMTP client without validating that the target address is external. An attacker with organization notification-admin permission can create or modify email notification templates to point to internal, loopback, link-local, or reserved addresses, triggering raw TCP connections from the controller task process. The connection results are reflected back, providing a three-state port scan oracle over the internal control-plane network, including the Kubernetes API. Additionally, if a shared organization template contains stored SMTP credentials, these can be sent to an attacker-controlled server. The flaw is due to missing connect-target validation in the email backend, unlike other notification backends that have been hardened. The fix involves validating and rejecting private, loopback, link-local, and reserved destinations for all notification backends. Red Hat notes this validation currently exists only on the 2.7 branch.

An authenticated user with notification-admin permissions can perform internal network reconnaissance by leveraging the SSRF vulnerability to scan ports within the cluster network, potentially exposing internal services such as the Kubernetes API. Furthermore, if SMTP credentials are stored in shared templates, these credentials can be exfiltrated to attacker-controlled servers, leading to credential compromise. The vulnerability impacts confidentiality and integrity but does not affect availability.

Red Hat has identified that the correct fix is to implement connect-target validation for all notification backends to reject private, loopback, link-local, and reserved addresses. This validation currently exists only on the 2.7 branch of the product. Users should upgrade to a version that includes this fix once available. Until then, restrict notification-admin permissions to trusted users and avoid storing SMTP credentials in shared templates. Patch status is not yet confirmed—check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-84721 for current remediation guidance.