From 952b755091d60067ad957480dbe9dc5d921355fa Mon Sep 17 00:00:00 2001
From: subotac <73706465+subotac@users.noreply.github.com>
Date: Thu, 6 Aug 2026 02:29:38 +0300
Subject: [PATCH] vm: preserve global function declaration restrictions

Keep the global proxy's DontDelete attribute when the sandbox also
contains the property, so lexical redeclarations are rejected.

Signed-off-by: subotac <73706465+subotac@users.noreply.github.com>
---
 src/node_contextify.cc                              | 13 +++++++++++++
 test/parallel/test-vm-global-restricted-property.js |  8 ++++++++
 2 files changed, 21 insertions(+)

diff --git a/src/node_contextify.cc b/src/node_contextify.cc
index 8f9dddf53cae..852184b18215 100644
--- a/src/node_contextify.cc
+++ b/src/node_contextify.cc
@@ -534,6 +534,19 @@ Intercepted ContextifyContext::PropertyQueryCallback(
     if (!maybe_attr.FromMaybe(false)) {
       return Intercepted::kNo;
     }
+
+    // Function declarations can be reflected as configurable sandbox
+    // properties while V8 tracks their non-configurable global bindings.
+    PropertyAttribute global_attr;
+    if (ctx->global_proxy()
+            ->GetRealNamedPropertyAttributes(context, property)
+            .To(&global_attr)) {
+      attr = static_cast<PropertyAttribute>(
+          static_cast<int>(attr) |
+          (static_cast<int>(global_attr) &
+           static_cast<int>(PropertyAttribute::DontDelete)));
+    }
+
     args.GetReturnValue().Set(attr);
     return Intercepted::kYes;
   } else {
diff --git a/test/parallel/test-vm-global-restricted-property.js b/test/parallel/test-vm-global-restricted-property.js
index e57cc8dc8546..6bb2b8c93aae 100644
--- a/test/parallel/test-vm-global-restricted-property.js
+++ b/test/parallel/test-vm-global-restricted-property.js
@@ -18,3 +18,11 @@ assert.throws(
   () => vm.runInContext('let foo = 2;', ctx),
   vm.runInContext('SyntaxError', ctx),
 );
+
+// Global function declarations create non-configurable bindings even
+// though the corresponding sandbox properties are configurable.
+vm.runInContext('function bar() {}', ctx);
+assert.throws(
+  () => vm.runInContext('let bar;', ctx),
+  vm.runInContext('SyntaxError', ctx),
+);