A flaw in Quay’s repository‑level mirror configuration lets a repository administrator supply an external_reference value that is not validated. When the Quay mirror worker processes the request, it uses Skopeo to make outbound network calls to the supplied address. Because the URL is not checked, the worker can reach arbitrary internal services, cloud metadata endpoints, or other resources that are normally off‑limits. The flaw is an SSRF, CWE‑918, and allows the attacker to trigger connections to unintended endpoints from within the Quay environment.

The vulnerability affects Red Hat Quay 3 and the Mirror Registry for Red Hat OpenShift 2. Any deployment of Quay 3 that enables repository‑level mirroring is susceptible. Organization‑level mirroring is not impacted because it includes proper URL validation.

The CVSS score of 6.8 indicates moderate severity. The EPSS score is below 1 %, showing that exploitation is currently unlikely. The vulnerability is not listed in the CISA KEV catalog. Exploitation requires a user with repository‑administrator privileges to create or update a mirror configuration, after which the Quay mirror worker runs an unvalidated Skopeo request on behalf of the cluster. Since the request originates from within the cluster, an attacker would need internal network visibility or the ability to reach the target endpoint to benefit from the SSRF. The most effective mitigations rely on restricting repository‑level mirroring privileges and limiting the mirror worker’s network egress to prevent unintended access to internal resources.