diff -rupN --no-dereference Pillow-5.4.1/src/libImaging/PcxDecode.c Pillow-5.4.1-new/src/libImaging/PcxDecode.c
--- Pillow-5.4.1/src/libImaging/PcxDecode.c	2020-02-13 14:44:21.491015777 +0100
+++ Pillow-5.4.1-new/src/libImaging/PcxDecode.c	2020-02-13 14:44:21.593015020 +0100
@@ -25,6 +25,9 @@ ImagingPcxDecode(Imaging im, ImagingCode
     if (strcmp(im->mode, "1") == 0 && state->xsize > state->bytes * 8) {
         state->errcode = IMAGING_CODEC_OVERRUN;
         return -1;
+    } else if (strcmp(im->mode, "P") == 0 && state->xsize > state->bytes) {
+        state->errcode = IMAGING_CODEC_OVERRUN;
+        return -1;
     }
 
     ptr = buf;
diff -rupN --no-dereference Pillow-5.4.1/Tests/test_image.py Pillow-5.4.1-new/Tests/test_image.py
--- Pillow-5.4.1/Tests/test_image.py	2020-02-13 14:44:21.592015027 +0100
+++ Pillow-5.4.1-new/Tests/test_image.py	2020-02-13 14:44:21.594015013 +0100
@@ -555,6 +555,17 @@ class TestRegistry(PillowTestCase):
         self.assertIsInstance(enc, MockEncoder)
         self.assertEqual(enc.args, ('RGB', 'args', 'extra'))
 
+    def test_overrun(self):
+        for file in [
+            "pcx_overrun2.bin",
+        ]:
+            im = Image.open(os.path.join("Tests/images", file))
+            try:
+                im.load()
+                self.assertFail()
+            except IOError as e:
+                self.assertEqual(str(e), "buffer overrun when reading image file")
+
     def test_encode_registry_fail(self):
         self.assertRaises(IOError, Image._getencoder, 'RGB',
                                                       'DoesNotExist',