Impact

Fleet's Helm deployer did not fully apply ServiceAccount impersonation in two code paths, allowing a tenant with git push access to a Fleet-monitored repository to read secrets from any namespace on every downstream cluster targeted by their GitRepo.

Helm lookup bypass: The Helm template engine ran Kubernetes API queries with the fleet-agent's cluster-admin credentials instead of the impersonated ServiceAccount. A chart template could therefore access resources beyond the tenant's RBAC scope.

valuesFrom bypass: Secret and ConfigMap references in fleet.yaml helm.valuesFrom were read using the fleet-agent's cluster-admin client. A tenant could reference resources in namespaces the impersonated ServiceAccount has no access to.
Both issues break Fleet's multi-tenant impersonation boundary. The leaked credentials may belong to external services, making the full impact non-deterministic.
Single-tenant deployments where all users are trusted are not affected.

Important:

• For the exposure of additional credentials, the final impact severity for confidentiality, integrity and availability is dependent on the permissions the leaked credentials have on their services.
• It is recommended to review for potentially leaked credentials in this scenario and to change them if deemed necessary.

Please consult the associated MITRE ATT&CK - Technique - Account Access Removal for further information about this category of attack.

Patches

Both issues are fixed by ensuring the Helm action configuration consistently uses the impersonated ServiceAccount credentials throughout all Helm operations.

Patched versions of Rancher include releases v2.14.1, v2.13.5, v2.12.9, and v2.11.13. For Rancher v2.10.11, users must manually update their Fleet deployment to versionv0.11.13.

Workarounds

No workaround fully mitigates the issue for multi-tenant deployments. The patches should be applied as soon as they are available.

The following measures reduce the attack surface but do not close either vulnerability:

• Restrict git push access to Fleet-monitored repositories to trusted users only. In a multi-tenant setup this removes the precondition entirely, but is often not operationally viable.
• Use GitRepoRestriction resources to limit which ServiceAccounts each namespace is allowed to use, restricting the set of users who can configure impersonation at all.
• Audit deployed chart templates for lookup calls and fleet.yaml files for cross-namespace valuesFrom references as a detective control.

References

If you have any questions or comments about this advisory:

• Reach out to the SUSE Rancher Security team for security related inquiries.
• Open an issue in the Rancher repository.
• Verify with our support matrix and product support lifecycle.