cilium-agent container can access the host via `hostPath` mount

### Impact An attacker with access to a Cilium agent pod can write to `/opt/cni/bin` due to a `hostPath` mount of that directory in the agent pod. By replacing the CNI binary with their own malicious binary and waiting for the creation of a new pod on the node, the attacker can gain access to the underlying node. ### Patches The issue has been fixed and is available on versions >=1.11.15, >=1.12.8, >=1.13.1. ### Workarounds [Kubernetes RBAC](https://kubernetes.io/docs/reference/access-authn-authz/rbac/) should be used to deny users and service accounts `exec` access to Cilium agent pods. In cases where a user requires `exec` access to Cilium agent pods, but should not have access to the underlying node, no workaround is possible. ### References * [PR containing resolution](https://github.com/cilium/cilium/pull/24075) ### Acknowledgements The Cilium community has worked together with members of Isovalent and Form3 to prepare these mitigations. Special thanks to Anastasios Koutlis, Daniel Teixeira, and Magdalena Oczadly for their cooperation. ### For more information If you have any questions or comments about this advisory, please reach out on [Slack](https://docs.cilium.io/en/latest/community/community/#slack). As usual, if you think you found a related vulnerability, we strongly encourage you to report security vulnerabilities to our private security mailing list: [email protected] - first, before disclosing them in any public forums. This is a private mailing list where only members of the Cilium internal security team are subscribed to, and is treated as top priority.

Quoted source text, attributed separately from HOL analysis.