Ensure an item is within the upper array boundaries before replacing it

2 files changed, 6 insertions, 1 deletions

diff --git a/jsonpatch.py b/jsonpatch.py
index 4f8a02b..1b90bfd 100644
--- a/jsonpatch.py
+++ b/jsonpatch.py
@@ -474,7 +474,7 @@ class ReplaceOperation(PatchOperation):
             return value
 
         if isinstance(subobj, MutableSequence):
-            if part > len(subobj) or part < 0:
+            if part >= len(subobj) or part < 0:
                 raise JsonPatchConflict("can't replace outside of list")
 
         elif isinstance(subobj, MutableMapping):
diff --git a/tests.py b/tests.py
index cd39b3b..6ecb017 100755
--- a/tests.py
+++ b/tests.py
@@ -602,6 +602,11 @@ class ConflictTests(unittest.TestCase):
         patch_obj = [ { "op": "replace", "path": "/foo/10", "value": 10} ]
         self.assertRaises(jsonpatch.JsonPatchConflict, jsonpatch.apply_patch, src, patch_obj)
 
+    def test_replace_oob_length(self):
+        src = {"foo": [0, 1]}
+        patch_obj = [ { "op": "replace", "path": "/foo/2", "value": 2} ]
+        self.assertRaises(jsonpatch.JsonPatchConflict, jsonpatch.apply_patch, src, patch_obj)
+
     def test_replace_missing(self):
         src = {"foo": 1}
         patch_obj = [ { "op": "replace", "path": "/bar", "value": 10} ]