CVE-2026-42965: Openshift/router: openshift/router: cloud metadata ssrf via fqdn-typed endpointslice bypasses destination validation
A flaw was found in the OpenShift Router. A user with EndpointSlice write access can exploit this vulnerability by creating a Service backed by an FQDN (Fully Qualified Domain Name) EndpointSlice that resolves to a cloud metadata endpoint. This allows the router to proxy requests to the cloud metadata endpoint, leading to the disclosure of instance credentials and other sensitive metadata. This bypasses previous security measures for validating IP addresses.
Other sources
The OpenShift Router does not validate backend destinations resolved from FQDN-typed EndpointSlices. A user with EndpointSlice write access can create a Service backed by an FQDN EndpointSlice pointing to a hostname that resolves to 169.254.169.254 (e.g. 169-254-169-254.nip.io), then create a Route targeting that Service. The router proxies requests to the cloud metadata endpoint, allowing the attacker to retrieve instance credentials and other sensitive metadata. This bypasses the fix for CVE-2021-25737, which only validates IPv4/IPv6 addresses via ValidateEndpointIP() but not FQDN endpoints. IMDSv2 does not mitigate this because HAProxy runs as a hostNetwork process at Layer 7 and can perform the PUT/GET token exchange. This attack requires the IngressController to use HostNetwork endpoint publishing (default on bare metal/UPI, not on cloud providers).
— Red Hat
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
Ensure the IngressController is NOT using HostNetwork endpoint publishing (the vulnerability requires HostNetwork endpoint publishing, which is the default on bare metal/UPI and not on cloud providers).
- Compensating control
Mitigate the SSRF path by blocking egress from the OpenShift Router/IngressController to the cloud metadata service IP/hostname that resolves to 169.254.169.254 (e.g., deny traffic to 169.254.169.254) so proxied requests cannot reach instance metadata endpoints.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-42965?
The severity of CVE-2026-42965 is rated as high with a score of 7.7.
How do I fix CVE-2026-42965?
To fix CVE-2026-42965, update to the latest version of the Red Hat OpenShift Router that addresses this vulnerability.
What type of vulnerability is CVE-2026-42965?
CVE-2026-42965 is classified as a Server-Side Request Forgery (SSRF) vulnerability.
Who is affected by CVE-2026-42965?
Users of Red Hat OpenShift Router with EndpointSlice write access are affected by CVE-2026-42965.
What impact does CVE-2026-42965 have?
CVE-2026-42965 allows an attacker to proxy requests to cloud metadata endpoints, potentially exposing sensitive information.