Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.36.10, 1.37.6, 1.38.4, and 1.39.1, Envoy forwards data for a configured non-WebSocket HTTP upgrade before the upstream accepts the upgrade. An unauthenticated HTTP/2 client can place a complete HTTP/1.1 request in extended CONNECT data; Envoy downgrades the request, writes the data unframed to a keep-alive HTTP/1.1 upstream, and returns the socket to the shared pool while the smuggled response remains queued. A different downstream client can then receive the attackers response. The relevant scope boundary is that webSocket upgrades, plain CONNECT, disabled backend keep-alive, per-downstream pools, and max_requests_per_connection set to 1 are not affected by the demonstrated path. This issue is fixed in versions 1.36.10, 1.37.6, 1.38.4, and 1.39.1.
Weakness
The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Red Hat OpenShift Service Mesh 3.0 | RedHat | openshift-service-mesh/istio-proxyv2-rhel9:1788296328 | * |
| Red Hat OpenShift Service Mesh 3.1 | RedHat | openshift-service-mesh/istio-proxyv2-rhel9:1788294715 | * |
| Red Hat OpenShift Service Mesh 3.2 | RedHat | openshift-service-mesh/istio-proxyv2-rhel9:1788329366 | * |
| Red Hat OpenShift Service Mesh 3.3 | RedHat | openshift-service-mesh/istio-proxyv2-rhel9:1788327866 | * |
| Red Hat OpenShift Service Mesh 3.4 | RedHat | openshift-service-mesh/istio-proxyv2-rhel9:1788333924 | * |
Extended Description
HTTP requests or responses (“messages”) can be malformed or unexpected in ways that cause web servers or clients to interpret the messages in different ways than intermediary HTTP agents such as load balancers, reverse proxies, web caching proxies, application firewalls, etc. For example, an adversary may be able to add duplicate or different header fields that a client or server might interpret as one set of messages, whereas the intermediary might interpret the same sequence of bytes as a different set of messages. For example, discrepancies can arise in how to handle duplicate headers like two Transfer-encoding (TE) or two Content-length (CL), or the malicious HTTP message will have different headers for TE and CL. The inconsistent parsing and interpretation of messages can allow the adversary to “smuggle” a message to the client/server without the intermediary being aware of it. This weakness is usually the result of the usage of outdated or incompatible HTTP protocol versions in the HTTP agents.
Potential Mitigations
Related Attack Patterns
References
- https://github.com/envoyproxy/envoy/commit/309855626966cff176155c821043ed3b44671361
- https://github.com/envoyproxy/envoy/commit/3c7998545a9c9fb3933a4bc1907d92f0e752bc2b
- https://github.com/envoyproxy/envoy/commit/4633b8cce3d15b8734eefe232e30c12b0140b91c
- https://github.com/envoyproxy/envoy/commit/bd6711f2617658e28dfa3df3dace6bfe3cfc0766
- https://github.com/envoyproxy/envoy/releases/tag/v1.36.10
- https://github.com/envoyproxy/envoy/releases/tag/v1.37.6
- https://github.com/envoyproxy/envoy/releases/tag/v1.38.4
- https://github.com/envoyproxy/envoy/releases/tag/v1.39.1
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-3vhp-c83q-jqc2
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-3vhp-c83q-jqc2