File GraphicsMagick-CVE-2026-28690.patch of Package GraphicsMagick

Index: GraphicsMagick-1.3.46/coders/png.c
===================================================================
--- GraphicsMagick-1.3.46.orig/coders/png.c
+++ GraphicsMagick-1.3.46/coders/png.c
@@ -10205,6 +10205,14 @@ static unsigned int WriteMNGImage(const
   have_mng_structure=MagickTrue;
 
   write_mng=LocaleCompare(image_info->magick,"MNG") == 0;
+
+  /*
+    MNG only supports a color palette up to 256 colors
+   */
+  if ((write_mng != MagickFalse) && (image->storage_class == PseudoClass) &&
+      (image->colors > 256))
+    image->storage_class=DirectClass;
+
   mng_info->write_png8=LocaleCompare(image_info->magick,"PNG8") == 0;
   mng_info->write_png24=LocaleCompare(image_info->magick,"PNG24") == 0;
   mng_info->write_png32=LocaleCompare(image_info->magick,"PNG32") == 0;