--- a/libraw/libraw_const.h.orig	2020-07-03 11:22:46.761804592 -0500
+++ b/libraw/libraw_const.h	2020-07-03 11:23:02.620793431 -0500
@@ -24,6 +24,12 @@
 #define LIBRAW_MAX_ALLOC_MB 2048L
 #endif
 
+/* limit thumbnail size, default is 512Mb*/
+#ifndef LIBRAW_MAX_THUMBNAIL_MB
+#define LIBRAW_MAX_THUMBNAIL_MB 512L
+#endif
+
+
 /* Change to non-zero to allow (broken) CRW (and other) files metadata 
    loop prevention */
 #ifndef LIBRAW_METADATA_LOOP_PREVENTION
--- a/src/libraw_cxx.cpp.orig	2020-07-03 11:20:21.810906602 -0500
+++ b/src/libraw_cxx.cpp	2020-07-03 11:37:33.802869028 -0500
@@ -3712,6 +3712,21 @@
     return NULL;
   }
 
+  if (T.tlength < 64u)
+  {
+      if (errcode)
+          *errcode = EINVAL;
+      return NULL;
+  }
+
+  if (INT64(T.tlength) > 1024ULL * 1024ULL * LIBRAW_MAX_THUMBNAIL_MB)
+  {
+      if (errcode)
+          *errcode = LIBRAW_TOO_BIG;
+      return NULL;
+  }
+
+
   if (T.tformat == LIBRAW_THUMBNAIL_BITMAP)
   {
     libraw_processed_image_t *ret = (libraw_processed_image_t *)::malloc(sizeof(libraw_processed_image_t) + T.tlength);
@@ -3976,6 +3991,12 @@
   if (ID.toffset + est_datasize > ID.input->size() + THUMB_READ_BEYOND)
     throw LIBRAW_EXCEPTION_IO_EOF;
 
+  if(INT64(T.theight) * INT64(T.twidth) > 1024ULL * 1024ULL * LIBRAW_MAX_THUMBNAIL_MB)
+      throw LIBRAW_EXCEPTION_IO_CORRUPT;
+
+  if (INT64(T.theight) * INT64(T.twidth) < 64ULL)
+      throw LIBRAW_EXCEPTION_IO_CORRUPT;
+
   // some kodak cameras
   ushort s_height = S.height, s_width = S.width, s_iwidth = S.iwidth, s_iheight = S.iheight;
   ushort s_flags = libraw_internal_data.unpacker_data.load_flags;
@@ -4237,6 +4258,25 @@
   CHECK_ORDER_LOW(LIBRAW_PROGRESS_IDENTIFY);
   CHECK_ORDER_BIT(LIBRAW_PROGRESS_THUMB_LOAD);
 
+#define THUMB_SIZE_CHECKT(A) \
+  do { \
+    if (INT64(A) > 1024ULL * 1024ULL * LIBRAW_MAX_THUMBNAIL_MB) throw LIBRAW_EXCEPTION_IO_CORRUPT; \
+    if (INT64(A) > 0 &&  INT64(A) < 64ULL)        throw LIBRAW_EXCEPTION_IO_CORRUPT; \
+  } while (0)
+
+#define THUMB_SIZE_CHECKTNZ(A) \
+  do { \
+    if (INT64(A) > 1024ULL * 1024ULL * LIBRAW_MAX_THUMBNAIL_MB) throw LIBRAW_EXCEPTION_IO_CORRUPT; \
+    if (INT64(A) < 64ULL)        throw LIBRAW_EXCEPTION_IO_CORRUPT; \
+  } while (0)
+
+
+#define THUMB_SIZE_CHECKWH(W,H) \
+  do { \
+    if (INT64(W)*INT64(H) > 1024ULL * 1024ULL * LIBRAW_MAX_THUMBNAIL_MB) throw LIBRAW_EXCEPTION_IO_CORRUPT; \
+    if (INT64(W)*INT64(H) < 64ULL)        throw LIBRAW_EXCEPTION_IO_CORRUPT; \
+  } while (0)
+
   try
   {
     if (!libraw_internal_data.internal_data.input)
@@ -4267,6 +4307,7 @@
 
         if (INT64(ID.toffset) + tsize > ID.input->size() + THUMB_READ_BEYOND)
           throw LIBRAW_EXCEPTION_IO_EOF;
+        THUMB_SIZE_CHECKT(tsize);
       }
       else
       {
@@ -4280,6 +4321,7 @@
       ID.input->seek(ID.toffset, SEEK_SET);
       if (write_thumb == &LibRaw::jpeg_thumb)
       {
+        THUMB_SIZE_CHECKTNZ(T.tlength);
         if (T.thumb)
           free(T.thumb);
         T.thumb = (char *)malloc(T.tlength);
@@ -4326,6 +4368,7 @@
       {
         if (t_bytesps > 1)
           throw LIBRAW_EXCEPTION_IO_CORRUPT; // 8-bit thumb, but parsed for more bits
+        THUMB_SIZE_CHECKWH(T.twidth, T.theight);
         int t_length = T.twidth * T.theight * t_colors;
 
         if (T.tlength && T.tlength < t_length) // try to find tiff ifd with needed offset
@@ -4351,8 +4394,12 @@
                 T.tcolors = 1;
             }
             T.tlength = total_size;
+            THUMB_SIZE_CHECKTNZ(T.tlength);
             if (T.thumb)
               free(T.thumb);
+            
+            THUMB_SIZE_CHECKTNZ(T.tlength);
+            
             T.thumb = (char *)malloc(T.tlength);
             merror(T.thumb, "ppm_thumb()");
 
@@ -4400,10 +4447,15 @@
         if (t_bytesps > 2)
           throw LIBRAW_EXCEPTION_IO_CORRUPT; // 16-bit thumb, but parsed for more bits
         int o_bps = (imgdata.params.raw_processing_options & LIBRAW_PROCESSING_USE_PPM16_THUMBS) ? 2 : 1;
+        THUMB_SIZE_CHECKWH(T.twidth, T.theight);
         int o_length = T.twidth * T.theight * t_colors * o_bps;
         int i_length = T.twidth * T.theight * t_colors * 2;
         if (!T.tlength)
           T.tlength = o_length;
+        THUMB_SIZE_CHECKTNZ(o_length);
+        THUMB_SIZE_CHECKTNZ(i_length);
+        THUMB_SIZE_CHECKTNZ(T.tlength);
+
         ushort *t_thumb = (ushort *)calloc(i_length, 1);
         ID.input->read(t_thumb, 1, i_length);
         if ((libraw_internal_data.unpacker_data.order == 0x4949) == (ntohs(0x1234) == 0x1234))