Medium [CVE-2026-15927] repo-level mirror accepts external_reference without URL validation
This medium-severity Red Hat Linux advisory covers CVE-2026-15927 affecting Red Hat Quay 3.12, Red Hat Quay 3.15, Red Hat Quay 3.17.
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Summary
A flaw was found in Red Hat Quay's repository-level mirror configuration feature. The POST and PUT handlers in endpoints/api/mirror.py accept an external_reference parameter without SSRF validation, unlike the organization-level mirror handlers which apply validate_external_registry_url().
A repository administrator can supply a crafted hostname that causes the Quay mirror worker to make requests via Skopeo to internal network services, cloud metadata endpoints, or other resources not intended to be reachable from the Quay application. This risk is limited to actions performed by an authenticated administrator.
Red Hat severity: Important — CVSS 6.8 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N). Weakness: CWE-918.
Affected Red Hat products: Red Hat Quay 3.1; Red Hat Quay 3.12; Red Hat Quay 3.15; Red Hat Quay 3.17; Red Hat Quay 3.9; mirror registry for Red Hat OpenShift 2. Will not fix / out of support: mirror registry for Red Hat OpenShift 2.
Red Hat fixing advisory: RHSA-2026:53520, RHSA-2026:52968, RHSA-2026:63307, RHSA-2026:54395, RHSA-2026:50931.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
- quay/quay-rhel8:1786395065
- quay/quay-rhel8:1786170635
- quay/quay-rhel8:1788191755
- quay/quay-rhel9:1786181981
- quay/quay-rhel8:1785950004
- RHSA-2026:53520
- RHSA-2026:52968
- RHSA-2026:63307
- RHSA-2026:54395
- RHSA-2026:50931
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
Mitigation checklist
- Restrict network egress from Quay mirror worker pods/containers using network policies or firewall rules to block access to internal network ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) and cloud metadata endpoints (169.254.169.254, metadata.google.internal). Limit repository creation and admin privileges to trusted users via Quay's RBAC configuration. If repository-level mirroring is not required, disable the feature or restrict access to the mirror API endpoints through a reverse proxy.
Official advisory · high-confidence parse· fetched 3 hours ago·verify at source
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