A vulnerability has been identified within Rancher Manager where the Fleet agent wrote resources to downstream clusters using its own cluster-admin credentials instead of the ServiceAccount pinned to the deployment. It affects multi-tenancy environments where different tenants share the same downstream clusters, for example different privileged or untrusted teams inside the same organization. This could lead to overwritten configuration files.

This issue affected SUSE Rancher Fleet 0.16 before 0.16.2, 0.15 before 0.15.7, and 0.14 before 0.14.11.

A cross-tenant authorization issue was discovered in SUSE Rancher Fleet. During agent-initiated cluster registration, cluster labels supplied by the registering agent, including labels in the reserved management.cattle.io/ namespace such as the cluster display name label, were applied to the resulting upstream Cluster object. Because Fleet resolves GitRepo and Bundle targets from those cluster labels, a party able to register a cluster into a Fleet workspace namespace shared with other tenants could cause its own cluster to satisfy targeting rules that administrators intended for a different cluster. This affects SUSE Rancher Fleet 0.16 before 0.16.1, 0.15 before 0.15.6, 0.14 before 0.14.10, 0.13 before 0.13.15, 0.12 before 0.12.19 and older versions.

Impact A vulnerability has been identified in Fleet when the webhook endpoint is configured without a secret; an attacker can forge webhook requests. The attacker doesn't need to know the specific repository or path configured in the GitRepo resource to make Fleet process these requests.

An attacker can exploit this vulnerability to cause the following impacts: 1. Trigger continuous repository re-cloning, which increases network traffic and can deplete resources on the management cluster. 2. Downgrade running services to any historical revision available in the remote Git repository. This risk applies if the attacker has read access to the target Git repository and knows its configured path.

Please consult the associated MITRE ATT&CK - Technique - T1499.004: Endpoint Denial of Service for further information about this category of attack.

Patches To resolve this vulnerability, upgrade Fleet to a patched version. This upgrade version escapes the URL and path to the remote repository received from webhooks, which prevents regular expressions from being used as a replacement for the URL and path.

Patched versions of Fleet include releases v0.15.2, v0.14.6, 0.13.11, and v0.12.15.

Workarounds If you can't upgrade to a fixed version, please make sure to only enable webhooks with a shared secret.

Credits

This security issue was reported by the following collaborators according to our responsible disclosure policy:

- Radisauskas Arnoldas from NATO and the NATO Cyber Security Centre (NCSC).

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.