--- qt-everywhere-src-6.9.0/qtbase/src/network/access/qnetworkreplywasmimpl.cpp	2025-05-13 10:57:39.168157000 +0200
+++ qt-everywhere-src-6.9.0-new/qtbase/src/network/access/qnetworkreplywasmimpl.cpp	2025-05-13 11:05:02.353600500 +0200
@@ -428,8 +428,9 @@
 
         for (int i = 0; i < headers.size(); i++) {
             if (headers.at(i).contains(':')) { // headers include final \x00, so skip
-                QByteArray headerName = headers.at(i).split(':').at(0).trimmed();
-                QByteArray headersValue = headers.at(i).split(':').at(1).trimmed();
+                qsizetype splitPos = headers.at(i).indexOf(':');
+                QByteArray headerName = headers.at(i).first(splitPos).trimmed();
+                QByteArray headersValue = headers.at(i).sliced(splitPos+1).trimmed();
 
                 if (headerName.isEmpty() || headersValue.isEmpty())
                     continue;