GHSA-xg58-75qf-9r67 Cilium's Layer 7 policy enforcement may not occur in policies with wildcarded port ranges

• Go github.com/cilium/cilium: >= 1.16.0, < 1.16.4 → fixed in 1.16.4

Impact For users with the following configuration: • An allow policy that selects a Layer 3 identity and a port range AND • A Layer 7 allow policy that selects a specific port within the first policy's range then Layer 7 enforcement would not occur for the traffic selected by the Layer 7 policy. This issue only affects users who use Cilium's port range functionality, which was introduced in Cilium v1.16. For reference, an example of a pair of policies that would trigger this issue is: ``` apiVersion: "cilium.io/v2" kind: CiliumNetworkPolicy metadata: name: "layer-3-and-4" spec: endpointSelector: matchLabels: app: service ingress: • fromCIDR: • 192.168.60.0/24 toPorts: • ports: • port: "80" endPort: 444 protocol: TCP ``` and ``` apiVersion: "cilium.io/v2" kind: CiliumNetworkPolicy metadata: name: "layer-4-and-7" spec: endpointSelector: matchLabels: app: service ingress: toPorts: • ports: • port: "80" protocol: TCP rules: http: • method: "GET" path: "/public" ``` In the above example, requests would be permitted to all HTTP paths on matching endpoints, rather than just `GET` requests to the `/public` path as intended by the `layer-4-and-7` policy. In patched versions of Cilium, the `layer-4-and-7` rule would take precedence over the `layer-3-and-4` rule. Patches This issue is patched in https://github.com/cilium/cilium/pull/35150. This issue affects Cilium v1.16 between v1.16.0 and v1.16.3 inclusive. This issue is patched in Cilium v1.16.4. Workarounds Users with network policies that match the pattern described above can work around the issue by rewriting any policies that use port ranges to individually specify the ports permitted for traffic. Acknowledgements The Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @jrajahalme for resolving this issue. 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 affecting Cilium, we strongly encourage you to report it to our security mailing list at [email protected]. This is a private mailing list for the Cilium security team, and your report will be treated as top priority.