api: Don't HTML escape application/json responses

pkg/api/handlers/utils/handler.go

@@ -120,7 +120,7 @@ func WriteJSON(w http.ResponseWriter, code int, value interface{}) {
 	w.WriteHeader(code)
 
 	coder := json.NewEncoder(w)
-	coder.SetEscapeHTML(true)
+	coder.SetEscapeHTML(false)
 	if err := coder.Encode(value); err != nil {
 		logrus.Errorf("Unable to write json: %q", err)
 	}

pkg/api/handlers/utils/handler_test.go

@@ -3,6 +3,9 @@
 package utils
 
 import (
+	"net/http/httptest"
+	"reflect"
+	"strings"
 	"testing"
 )
 
@@ -53,3 +56,54 @@ func TestErrorEncoderFuncOmit(t *testing.T) {
 		t.Errorf("the `errs` field shouldn't have been omitted")
 	}
 }
+
+func TestWriteJSONNoHTMLEscape(t *testing.T) {
+	// Test that WriteJSON does not HTML-escape JSON content
+	// This test verifies the fix for issue #17769
+
+	recorder := httptest.NewRecorder()
+
+	// Test data with characters that would be HTML-escaped
+	testData := map[string]string{
+		"message": "Hello <world> & \"friends\"",
+		"script":  "<script>alert('test')</script>",
+		"url":     "https://example.com/path?param=value&other=<test>",
+	}
+
+	WriteJSON(recorder, 200, testData)
+
+	// Check response headers
+	if contentType := recorder.Header().Get("Content-Type"); contentType != "application/json" {
+		t.Errorf("Expected Content-Type 'application/json', got '%s'", contentType)
+	}
+
+	// Check that response contains unescaped characters
+	body := recorder.Body.String()
+
+	// These characters should NOT be HTML-escaped in JSON responses
+	// (but quotes are still properly JSON-escaped)
+	expectedUnescaped := []string{
+		"<world>",
+		"&",
+		"\\\"friends\\\"", // JSON-escaped quotes, not HTML-escaped
+		"<script>",
+		"<test>",
+	}
+
+	for _, expected := range expectedUnescaped {
+		if !strings.Contains(body, expected) {
+			t.Errorf("Expected unescaped string '%s' in response body, got: %s", expected, body)
+		}
+	}
+
+	// Verify we can parse the JSON back
+	var parsed map[string]string
+	if err := json.Unmarshal([]byte(body), &parsed); err != nil {
+		t.Errorf("Failed to parse JSON response: %v", err)
+	}
+
+	// Verify the data matches what we sent
+	if !reflect.DeepEqual(parsed, testData) {
+		t.Errorf("Parsed message doesn't match original: got %v, want %v", parsed, testData)
+	}
+}