diff --git a/news/4237.bugfix.md b/news/4237.bugfix.md
new file mode 100644
index 0000000000..8e5ffa17e7
--- /dev/null
+++ b/news/4237.bugfix.md
@@ -0,0 +1 @@
+Fix broken CSS on 404 pages inside private folders @dobri1408
diff --git a/src/Products/CMFPlone/browser/exceptions.py b/src/Products/CMFPlone/browser/exceptions.py
index 0d843bf93b..7d4797e9c1 100644
--- a/src/Products/CMFPlone/browser/exceptions.py
+++ b/src/Products/CMFPlone/browser/exceptions.py
@@ -30,7 +30,15 @@ def __call__(self):
             # and sets the proper location header
             return
 
-        self.context = self.__parent__
+        # Always use portal root as context to ensure resources load correctly
+        current = self.__parent__
+        while hasattr(current, "__parent__") and current.__parent__ is not None:
+            if hasattr(current, "meta_type") and current.meta_type == "Plone Site":
+                break
+            current = current.__parent__
+
+        self.context = current
+        self.__parent__ = current  # Also update __parent__ to ensure consistency
         request = self.request
 
         exc_type, value, traceback = sys.exc_info()