diff -urNp a/plug-ins/common/file-tga.c b/plug-ins/common/file-tga.c
--- a/plug-ins/common/file-tga.c	2025-06-14 14:36:28.298535906 +0200
+++ b/plug-ins/common/file-tga.c	2025-06-14 14:50:52.545808264 +0200
@@ -555,7 +555,7 @@ load_image (const gchar  *filename,
   switch (info.imageType)
     {
       case TGA_TYPE_MAPPED:
-        if (info.bpp != 8)
+        if (info.bpp != 8 || !info.colorMapLength)
           {
             g_message ("Unhandled sub-format in '%s' (type = %u, bpp = %u)",
                        gimp_filename_to_utf8 (filename),
@@ -870,32 +870,46 @@ apply_colormap (guchar       *dest,
                 guint         width,
                 const guchar *cmap,
                 gboolean      alpha,
-                guint16       index)
+                guint16       colorMapIndex,
+                guint16       colorMapLength)
 {
   guint x;
+  gint  errcnt = 0;
 
-  if (alpha)
-    {
-      for (x = 0; x < width; x++)
-        {
-          *(dest++) = cmap[(*src - index) * 4];
-          *(dest++) = cmap[(*src - index) * 4 + 1];
-          *(dest++) = cmap[(*src - index) * 4 + 2];
-          *(dest++) = cmap[(*src - index) * 4 + 3];
-
-          src++;
-        }
-    }
-  else
+  for (x = 0; x < width; x++)
     {
-      for (x = 0; x < width; x++)
-        {
-          *(dest++) = cmap[(*src - index) * 3];
-          *(dest++) = cmap[(*src - index) * 3 + 1];
-          *(dest++) = cmap[(*src - index) * 3 + 2];
+      guchar entryIndex = src[x] - colorMapIndex;
 
-          src++;
-        }
+      if (src[x] < colorMapIndex || entryIndex >= colorMapLength) {
+        /* On Windows the error console can run out of resources when
+         * producing a huge amount of messages. This can happen when using
+         * fuzzed test images. This causes unresponsiveness at first and
+         * finally crashes GIMP. Eventually this needs to be fixed at the
+         * source, but for now let's limit the error messages to 10
+         * per line (this function is called once per read_line). */
+        if (errcnt < 10)
+          {
+            g_message ("Unsupported colormap entry: %u",
+                       src[x]);
+          }
+        else if (errcnt == 10)
+          {
+            g_message ("Too many colormap errors. Image may be corrupt.");
+          }
+        errcnt++;
+        entryIndex = 0;
+      }
+
+      if (alpha) {
+          *(dest++) = cmap[entryIndex * 4];
+          *(dest++) = cmap[entryIndex * 4 + 1];
+          *(dest++) = cmap[entryIndex * 4 + 2];
+          *(dest++) = cmap[entryIndex * 4 + 3];
+      } else {
+          *(dest++) = cmap[entryIndex * 3];
+          *(dest++) = cmap[entryIndex * 3 + 1];
+          *(dest++) = cmap[entryIndex * 3 + 2];
+      }
     }
 }
 
@@ -951,7 +965,7 @@ read_line (FILE         *fp,
       gboolean has_alpha = (info->alphaBits > 0);
 
       apply_colormap (row, buffer, info->width, convert_cmap, has_alpha,
-                      info->colorMapIndex);
+                      info->colorMapIndex, info->colorMapLength);
     }
   else if (info->imageType == TGA_TYPE_MAPPED)
     {
@@ -961,7 +975,7 @@ read_line (FILE         *fp,
     }
   else
     {
-      memcpy (row, buffer, info->width * drawable->bpp);
+      memcpy (row, buffer, info->width * info->bytes);
     }
 }
 
@@ -993,9 +1007,9 @@ ReadImage (FILE        *fp,
       cmap_bytes = (info->colorMapSize + 7 ) / 8;
       tga_cmap = g_new (guchar, info->colorMapLength * cmap_bytes);
 
-      if (info->colorMapSize > 24)
+      if (info->colorMapSize > 24  || info->alphaBits > 0)
         {
-          /* indexed + full alpha => promoted to RGBA */
+          /* indexed + full alpha, or alpha exists => promoted to RGBA */
           itype = GIMP_RGB;
           dtype = GIMP_RGBA_IMAGE;
           convert_cmap = g_new (guchar, info->colorMapLength * 4);
@@ -1007,13 +1021,6 @@ ReadImage (FILE        *fp,
           dtype = GIMP_RGB_IMAGE;
           convert_cmap = g_new (guchar, info->colorMapLength * 3);
         }
-      else if (info->alphaBits > 0)
-        {
-          /* if alpha exists here, promote to RGB */
-          itype = GIMP_RGB;
-          dtype = GIMP_RGBA_IMAGE;
-          convert_cmap = g_new (guchar, info->colorMapLength * 4);
-        }
       else
         {
           itype = GIMP_INDEXED;