diff --git a/libraw/libraw_const.h b/libraw/libraw_const.h
index aaeba8b1..9327d87a 100644
--- a/libraw/libraw_const.h
+++ b/libraw/libraw_const.h
@@ -20,7 +20,14 @@ it under the terms of the one of two licenses as you choose:
 #define LIBRAW_DEFAULT_ADJUST_MAXIMUM_THRESHOLD 0.75
 #define LIBRAW_DEFAULT_AUTO_BRIGHTNESS_THRESHOLD 0.01
 /* limit allocation size, default is 2Gb */
+#ifndef LIBRAW_MAX_ALLOC_MB_DEFAULT
 #define LIBRAW_MAX_ALLOC_MB_DEFAULT 2048L
+#endif
+
+/* limit thumbnail size, default is 512Mb*/
+#ifndef LIBRAW_MAX_THUMBNAIL_MB
+#define LIBRAW_MAX_THUMBNAIL_MB 512L
+#endif
 
 /* Check if enough file space exists before tag read */
 #ifndef LIBRAW_NO_IOSPACE_CHECK
diff --git a/src/decoders/unpack_thumb.cpp b/src/decoders/unpack_thumb.cpp
index fa4e2bfc..24ccff3e 100644
--- a/src/decoders/unpack_thumb.cpp
+++ b/src/decoders/unpack_thumb.cpp
@@ -33,6 +33,25 @@ int LibRaw::unpack_thumb(void)
   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)
@@ -65,6 +84,7 @@ int LibRaw::unpack_thumb(void)
 
         if (INT64(ID.toffset) + tsize > ID.input->size() + THUMB_READ_BEYOND)
           throw LIBRAW_EXCEPTION_IO_EOF;
+        THUMB_SIZE_CHECKT(tsize);
       }
 #else
 	if (0) {}
@@ -82,6 +102,8 @@ int LibRaw::unpack_thumb(void)
       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);
@@ -132,6 +154,8 @@ int LibRaw::unpack_thumb(void)
         if (colors != 1 && colors != 3)
           return LIBRAW_UNSUPPORTED_THUMBNAIL;
 
+        THUMB_SIZE_CHECKWH(T.twidth, T.theight);
+
         int tlength = T.twidth * T.theight;
         if (T.thumb)
           free(T.thumb);
@@ -172,6 +196,7 @@ int LibRaw::unpack_thumb(void)
       else if (write_thumb == &LibRaw::rollei_thumb)
       {
         int i;
+        THUMB_SIZE_CHECKWH(T.twidth, T.theight);
         int tlength = T.twidth * T.theight;
         if (T.thumb)
           free(T.thumb);
@@ -198,6 +223,7 @@ int LibRaw::unpack_thumb(void)
         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 &&
@@ -219,6 +245,7 @@ int LibRaw::unpack_thumb(void)
                 T.tcolors = 1;
             }
             T.tlength = total_size;
+            THUMB_SIZE_CHECKTNZ(T.tlength);
             if (T.thumb)
               free(T.thumb);
             T.thumb = (char *)malloc(T.tlength);
@@ -254,6 +281,8 @@ int LibRaw::unpack_thumb(void)
         if (T.thumb)
           free(T.thumb);
 
+        THUMB_SIZE_CHECKTNZ(T.tlength);
+
         T.thumb = (char *)malloc(T.tlength);
         if (!T.tcolors)
           T.tcolors = t_colors;
@@ -278,6 +307,10 @@ int LibRaw::unpack_thumb(void)
         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) ==
diff --git a/src/postprocessing/mem_image.cpp b/src/postprocessing/mem_image.cpp
index e79c9217..4d2a8781 100644
--- a/src/postprocessing/mem_image.cpp
+++ b/src/postprocessing/mem_image.cpp
@@ -33,6 +33,20 @@ libraw_processed_image_t *LibRaw::dcraw_make_mem_thumb(int *errcode)
     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(
diff --git a/src/utils/thumb_utils.cpp b/src/utils/thumb_utils.cpp
index bf6d9bc5..418ba2de 100644
--- a/src/utils/thumb_utils.cpp
+++ b/src/utils/thumb_utils.cpp
@@ -25,6 +25,12 @@ void LibRaw::kodak_thumb_loader()
   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;