CVE-2023-41333: Bypass of namespace restrictions in CiliumNetworkPolicy
Impact
An attacker with the ability to create or modify CiliumNetworkPolicy objects in a particular namespace is able to affect traffic on an entire Cilium cluster, potentially bypassing policy enforcement in other namespaces.
By using a crafted endpointSelector that uses the DoesNotExist operator on the reserved:init label, the attacker can create policies that bypass namespace restrictions and affect the entire Cilium cluster. This includes potentially allowing or denying all traffic.
This attack requires API server access, as described in the Kubernetes API Server Attacker section of the Cilium Threat Model.
Patches
This issue was patched in https://github.com/cilium/cilium/pull/28007
This issue affects:
- Cilium <= v1.14.1 - Cilium <= v1.13.6 - Cilium <= v1.12.13
This issue has been resolved in:
- Cilium v1.14.2 - Cilium v1.13.7 - Cilium v1.12.14
Workarounds
An admission webhook can be used to prevent the use of endpointSelectors that use the DoesNotExist operator on the reserved:init label in CiliumNetworkPolicies.
Acknowledgements The Cilium community has worked together with members of Palantir and Isovalent to prepare these mitigations. Special thanks to @odinuge for reporting this issue and @joestringer for the fix.
For more information If you have any questions or comments about this advisory, please reach out on Slack.
If you think you have found a vulnerability in Cilium, we strongly encourage you to report it to our private security mailing list at security@cilium.io first, before disclosing it in any public forum. This is a private mailing list for Cilium's internal security team, and your report will be treated as top priority.
Other sources
Cilium is a networking, observability, and security solution with an eBPF-based dataplane. An attacker with the ability to create or modify CiliumNetworkPolicy objects in a particular namespace is able to affect traffic on an entire Cilium cluster, potentially bypassing policy enforcement in other namespaces. By using a crafted endpointSelector that uses the DoesNotExist operator on the reserved:init label, the attacker can create policies that bypass namespace restrictions and affect the entire Cilium cluster. This includes potentially allowing or denying all traffic. This attack requires API server access, as described in the Kubernetes API Server Attacker section of the Cilium Threat Model. This issue has been resolved in Cilium versions 1.14.2, 1.13.7, and 1.12.14. As a workaround an admission webhook can be used to prevent the use of endpointSelectors that use the DoesNotExist operator on the reserved:init label in CiliumNetworkPolicies.
— MITRE
Affected Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is the impact of CVE-2023-41333?
An attacker with the ability to create or modify CiliumNetworkPolicy objects in a particular namespace is able to affect traffic on an entire Cilium cluster, potentially bypassing policy enforcement in other namespaces.
How can an attacker exploit CVE-2023-41333?
By using a crafted `endpointSelector` that uses the `DoesNotExist`
Which software versions are affected by CVE-2023-41333?
Versions 1.12.14, 1.13.7, and 1.14.2 of the github.com/cilium/cilium package in Go are affected.
What is the severity of CVE-2023-41333?
The severity of CVE-2023-41333 is medium with a CVSS score of 6.9.
How can I fix CVE-2023-41333?
To fix CVE-2023-41333, update the github.com/cilium/cilium package to version 1.12.14, 1.13.7, or 1.14.2.