diff --git a/source/extensions/filters/http/ext_proc/ext_proc.cc b/source/extensions/filters/http/ext_proc/ext_proc.cc
index 7661048511ac..0ef4f84c8274 100644
--- a/source/extensions/filters/http/ext_proc/ext_proc.cc
+++ b/source/extensions/filters/http/ext_proc/ext_proc.cc
@@ -118,7 +118,13 @@ void Filter::setEncoderFilterCallbacks(Http::StreamEncoderFilterCallbacks& callb
 }
 
 Filter::StreamOpenState Filter::openStream() {
-  ENVOY_BUG(!processing_complete_, "openStream should not have been called");
+  // External processing is completed. This means there is no need to send any further
+  // message to the server for processing. Just return IgnoreError so the filter
+  // will return FilterHeadersStatus::Continue.
+  if (processing_complete_) {
+    ENVOY_LOG(debug, "External processing is completed when trying to open the gRPC stream");
+    return StreamOpenState::IgnoreError;
+  }
   if (!stream_) {
     ENVOY_LOG(debug, "Opening gRPC stream to external processor");
     stream_ = client_->start(*this, grpc_service_, decoder_callbacks_->streamInfo());
diff --git a/test/extensions/filters/http/ext_proc/unit_test_fuzz/ext_proc_corpus/crash-232906f11069ff930e29c13c1a3ae5a2c3202c57 b/test/extensions/filters/http/ext_proc/unit_test_fuzz/ext_proc_corpus/crash-232906f11069ff930e29c13c1a3ae5a2c3202c57
new file mode 100644
index 000000000000..9bfa96c62f75
--- /dev/null
+++ b/test/extensions/filters/http/ext_proc/unit_test_fuzz/ext_proc_corpus/crash-232906f11069ff930e29c13c1a3ae5a2c3202c57
@@ -0,0 +1,70 @@
+config {
+  grpc_service {
+    google_grpc {
+      target_uri: "test_uri"
+      channel_credentials {
+        ssl_credentials {
+          private_key {
+            inline_string: "/"
+          }
+        }
+      }
+      stat_prefix: "test_uri"
+      credentials_factory_name: "test_uri"
+      config {
+      }
+    }
+    initial_metadata {
+      key: "test_uri"
+    }
+  }
+  failure_mode_allow: true
+  processing_mode {
+    response_header_mode: SKIP
+  }
+  request_attributes: "("
+  response_attributes: "test_uri"
+  response_attributes: "9\000\000\000\000\000\000\000"
+  stat_prefix: "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000."
+}
+request {
+  headers {
+    headers {
+      key: "("
+    }
+    headers {
+      key: "test_uri"
+    }
+  }
+  http_body {
+    data: "\360\270\270\270\360\270\270\270\360\270\270\270\360\270\270\270\360\270\270\270\360\270\270\270\360\270\270\270\360\270\270\270\360\270\270\270\360\270\270\270\360\270\270\270\360\270\270\270\350\270\270"
+  }
+}
+response {
+  request_headers {
+    response {
+      header_mutation {
+        remove_headers: "f"
+        remove_headers: "f"
+      }
+    }
+  }
+  dynamic_metadata {
+    fields {
+      key: ""
+      value {
+      }
+    }
+    fields {
+      key: ""
+      value {
+      }
+    }
+  }
+  mode_override {
+    request_header_mode: SKIP
+    request_body_mode: BUFFERED
+    response_body_mode: BUFFERED
+    request_trailer_mode: SEND
+  }
+}