From 81d6efa641b6a1d4b3a161e47448609bf64e2074 Mon Sep 17 00:00:00 2001
From: Paul Zuehlcke <pbz@mozilla.com>
Date: Sat, 18 Jan 2025 17:10:55 +0000
Subject: [PATCH] Bug 1932555,  a=RyanVM

Original Revision: https://phabricator.services.mozilla.com/D231928

Differential Revision: https://phabricator.services.mozilla.com/D234663
---
 dom/ipc/ContentParent.cpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index a309bba661f1..692ed9aa19de 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -5623,8 +5623,15 @@ mozilla::ipc::IPCResult ContentParent::CommonCreateWindow(
   }
 
   // If we haven't found a chrome window to open in, just use the most recently
-  // opened one.
+  // opened non PBM window.
   if (!outerWin) {
+    // The parent was a private window but it's no longer available.
+    if (aOriginAttributes.mPrivateBrowsingId !=
+        nsIScriptSecurityManager::DEFAULT_PRIVATE_BROWSING_ID) {
+      aResult = NS_ERROR_FAILURE;
+      return IPC_OK();
+    }
+
     outerWin = nsContentUtils::GetMostRecentNonPBWindow();
     if (NS_WARN_IF(!outerWin)) {
       aResult = NS_ERROR_FAILURE;