diff -rupN kio-extras-19.12.3/thumbnail/imagecreator.cpp kio-extras-19.12.3-new/thumbnail/imagecreator.cpp
--- kio-extras-19.12.3/thumbnail/imagecreator.cpp	2020-03-03 20:33:29.000000000 +0100
+++ kio-extras-19.12.3-new/thumbnail/imagecreator.cpp	2020-04-17 03:13:31.630526008 +0200
@@ -34,6 +34,9 @@ bool ImageCreator::create(const QString
 {
     // create image preview
     QImageReader ir(path);
+    QSize sz = ir.size();
+    if(sz.width() > 10240 || sz.height() > 10240)
+        return false;
     ir.setDecideFormatFromContent(true);
     img = ir.read();
     if (img.isNull())