Envoy through 1.15.0 only considers the first value when multiple header values are present for some HTTP headers. Envoy’s setCopy() header map API does not replace all existing occurences of a non-inline header.
{ "cpes": [ "cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*" ], "severity": "High" }