Avoid prototype pollution when reading styles

1 files changed, 12 insertions, 0 deletions

diff --git a/test/docx/styles-reader.tests.js b/test/docx/styles-reader.tests.js
index b63bb6a..8f964c1 100644
--- a/test/docx/styles-reader.tests.js
+++ b/test/docx/styles-reader.tests.js
@@ -120,6 +120,18 @@ test('when multiple style elements have same style ID then only first element is
     assert.equal(styles.findTableStyleById("TableNormal").name, "Normal Table");
 });
 
+test('w:type of __proto__ does not cause prototype pollution', function() {
+    readStylesXml(
+        new XmlElement("w:styles", {}, [
+            new XmlElement("w:style", {"w:type": "__proto__", "w:styleId": "List1"}, [
+                new XmlElement("w:name", {"w:val": "List 1"}, [])
+            ])
+        ])
+    );
+
+    assert.equal({}["List1"], undefined);
+});
+
 function paragraphStyleElement(id, name) {
     return styleElement("paragraph", id, name);
 }