GHSA-cf3q-gqg7-3fm9

Envoy crashes when HTTP ext_proc processes local replies

### Summary Envoy's ext_proc HTTP filter is at risk of crashing if a local reply is sent to the external server due to the filter's life time issue. A known situation is the fail of a websocket handshake will trigger a local reply leading to the crash of Envoy. ### PoC If both websocket and ext_proc are enabled, a failed handshake will trigger a local reply, thus ext_proc will crash. ### Mitigation 1. Disable websocket traffic 2. Change the websocket response from backend to always return `101 Switch protocol` based on RFC. 3. Apply the patch and the ext_proc filter will not send the local reply that is generated by Envoy to the ext_proc server for processing. 4. Apply the patch that the router will cancel the upstream requests when sending a local reply. ### Impact Denial of service ### Reporter Vasilios Syrakis Fernando Cainelli