From d0b8a022bca356f8c2b079a51bf93edf75dbf85c Mon Sep 17 00:00:00 2001
From: Kershaw Chang <kershaw@mozilla.com>
Date: Tue, 2 Jun 2026 07:13:53 +0000
Subject: [PATCH] Bug 2034944 - Filter cookieStore change events by per-host
 domain-match in CookieStoreNotifier, r=necko-reviewers,valentin,baku

Differential Revision: https://phabricator.services.mozilla.com/D297135
---
 dom/cookiestore/CookieStoreNotifier.cpp | 14 ++++++++++++--
 dom/cookiestore/CookieStoreNotifier.h   |  2 ++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/dom/cookiestore/CookieStoreNotifier.cpp b/dom/cookiestore/CookieStoreNotifier.cpp
index 73f2b3e96173..1a6561fea357 100644
--- a/dom/cookiestore/CookieStoreNotifier.cpp
+++ b/dom/cookiestore/CookieStoreNotifier.cpp
@@ -47,13 +47,18 @@ already_AddRefed<CookieStoreNotifier> CookieStoreNotifier::Create(
     return nullptr;
   }
 
+  nsCString host;
+  if (NS_WARN_IF(NS_FAILED(principal->GetAsciiHost(host))) || host.IsEmpty()) {
+    return nullptr;
+  }
+
   nsCOMPtr<nsIObserverService> os = mozilla::services::GetObserverService();
   if (NS_WARN_IF(!os)) {
     return nullptr;
   }
 
   RefPtr<CookieStoreNotifier> notifier = new CookieStoreNotifier(
-      aCookieStore, baseDomain, principal->OriginAttributesRef());
+      aCookieStore, baseDomain, host, principal->OriginAttributesRef());
 
   nsresult rv =
       os->AddObserver(notifier,
@@ -68,9 +73,10 @@ already_AddRefed<CookieStoreNotifier> CookieStoreNotifier::Create(
 
 CookieStoreNotifier::CookieStoreNotifier(
     CookieStore* aCookieStore, const nsACString& aBaseDomain,
-    const OriginAttributes& aOriginAttributes)
+    const nsACString& aHost, const OriginAttributes& aOriginAttributes)
     : mCookieStore(aCookieStore),
       mBaseDomain(aBaseDomain),
+      mHost(aHost),
       mOriginAttributes(aOriginAttributes) {
   MOZ_ASSERT(NS_IsMainThread());
   MOZ_ASSERT(aCookieStore);
@@ -129,6 +135,10 @@ CookieStoreNotifier::Observe(nsISupports* aSubject, const char* aTopic,
     return NS_OK;
   }
 
+  if (!net::CookieCommons::DomainMatches(net::Cookie::Cast(cookie), mHost)) {
+    return NS_OK;
+  }
+
   bool isHttpOnly;
   rv = cookie->GetIsHttpOnly(&isHttpOnly);
   if (NS_WARN_IF(NS_FAILED(rv))) {
diff --git a/dom/cookiestore/CookieStoreNotifier.h b/dom/cookiestore/CookieStoreNotifier.h
index 7eefee65b353..b064293fc3e1 100644
--- a/dom/cookiestore/CookieStoreNotifier.h
+++ b/dom/cookiestore/CookieStoreNotifier.h
@@ -30,6 +30,7 @@ class CookieStoreNotifier final : public nsIObserver {
 
  private:
   CookieStoreNotifier(CookieStore* aCookieStore, const nsACString& aBaseDomain,
+                      const nsACString& aHost,
                       const OriginAttributes& aOriginAttributes);
   ~CookieStoreNotifier();
 
@@ -39,6 +40,7 @@ class CookieStoreNotifier final : public nsIObserver {
   CookieStore* mCookieStore;
 
   nsCString mBaseDomain;
+  nsCString mHost;
   OriginAttributes mOriginAttributes;
 
   nsTArray<RefPtr<Event>> mDelayedDOMEvents;