From 2f9bab74939ff70f7ef67188b6e06b1b7be2220d Mon Sep 17 00:00:00 2001
From: lukas-eu <62448426+lukas-eu@users.noreply.github.com>
Date: Wed, 22 Jul 2026 17:08:44 +0200
Subject: [PATCH 1/2] Block traversal to global method instances

---
 pointer.ts | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/pointer.ts b/pointer.ts
index 9b794c5..84b9d6f 100644
--- a/pointer.ts
+++ b/pointer.ts
@@ -72,8 +72,10 @@ export class Pointer {
       if (key == '__proto__' || key == 'constructor' || key == 'prototype') {
         continue
       }
-      // not sure if this the best way to handle non-existant paths...
-      value = (parent || {})[key]
+      value = undefined
+      if (parent && Object.prototype.hasOwnProperty.call(parent, key)) {
+        value = parent[key]
+      }
     }
     return {parent, key, value}
   }

From 30e174b33db03ebe041117bb4afdb44491e797dc Mon Sep 17 00:00:00 2001
From: lukas-eu <62448426+lukas-eu@users.noreply.github.com>
Date: Wed, 22 Jul 2026 17:10:02 +0200
Subject: [PATCH 2/2] Adding test

---
 test/issues.ts | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/test/issues.ts b/test/issues.ts
index 86f1191..74ef486 100644
--- a/test/issues.ts
+++ b/test/issues.ts
@@ -280,3 +280,12 @@ test('minimal array diff', t => {
   ]
   checkRoundtrip(t, input, output, expected_patch)
 })
+
+test('issues/2ndopp', t => {
+  t.true(({} as any).polluted === undefined, 'toString function should not be polluted')
+  const value = {}
+  applyPatch(value, [
+    {op: 'add', path: '/toString/polluted', value: 'Hello!'}
+  ])
+  t.true(({} as any).toString.polluted === undefined, 'toString function should still not be polluted')
+})