- http: fixed CVE-2019-15226 by adding a cached byte size in HeaderMap.
- http: added :ref:`max headers count <v1.11:envoy_api_field_core.HttpProtocolOptions.max_headers_count>` for http connections. The default limit is 100.
- upstream: runtime feature envoy.reloadable_features.max_response_headers_count overrides the default limit for upstream :ref:`max headers count <v1.11:envoy_api_field_Cluster.common_http_protocol_options>`
- http: added :ref:`common_http_protocol_options <v1.11:envoy_api_field_config.filter.network.http_connection_manager.v2.HttpConnectionManager.common_http_protocol_options>` Runtime feature envoy.reloadable_features.max_request_headers_count overrides the default limit for downstream :ref:`max headers count <v1.11:envoy_api_field_config.filter.network.http_connection_manager.v2.HttpConnectionManager.common_http_protocol_options>`
- regex: backported safe regex matcher fix for CVE-2019-15225.
- Use of :ref:`idle_timeout <v1.11:envoy_api_field_config.filter.network.http_connection_manager.v2.HttpConnectionManager.idle_timeout>` is deprecated. Use :ref:`common_http_protocol_options <v1.11:envoy_api_field_config.filter.network.http_connection_manager.v2.HttpConnectionManager.common_http_protocol_options>` instead.