diff --git a/dom/workers/ServiceWorker.h b/dom/workers/ServiceWorker.h
index 9c438ba5c22d..2eb4cff3b1cb 100644
--- a/dom/workers/ServiceWorker.h
+++ b/dom/workers/ServiceWorker.h
@@ -53,6 +53,8 @@ public:
   void
   GetScriptURL(nsString& aURL) const;
 
+  const ServiceWorkerInfo* Info() const { return mInfo; }
+
   void
   DispatchStateChange(ServiceWorkerState aState)
   {
diff --git a/dom/workers/ServiceWorkerEvents.cpp b/dom/workers/ServiceWorkerEvents.cpp
index 27d8ad343275..9fe80cec8d63 100644
--- a/dom/workers/ServiceWorkerEvents.cpp
+++ b/dom/workers/ServiceWorkerEvents.cpp
@@ -6,15 +6,18 @@
 
 #include "ServiceWorkerEvents.h"
 #include "ServiceWorkerClient.h"
+#include "ServiceWorkerManager.h"
 
 #include "nsIHttpChannelInternal.h"
 #include "nsINetworkInterceptController.h"
 #include "nsIOutputStream.h"
+#include "nsContentPolicyUtils.h"
 #include "nsContentUtils.h"
 #include "nsComponentManagerUtils.h"
 #include "nsServiceManagerUtils.h"
 #include "nsStreamUtils.h"
 #include "nsNetCID.h"
+#include "nsNetUtil.h"
 #include "nsSerializationHelper.h"
 #include "nsQueryObject.h"
 
@@ -104,13 +107,17 @@ namespace {
 class FinishResponse final : public nsRunnable
 {
   nsMainThreadPtrHandle<nsIInterceptedChannel> mChannel;
+  nsMainThreadPtrHandle<ServiceWorker> mServiceWorker;
   nsRefPtr<InternalResponse> mInternalResponse;
   ChannelInfo mWorkerChannelInfo;
+
 public:
   FinishResponse(nsMainThreadPtrHandle<nsIInterceptedChannel>& aChannel,
+                 nsMainThreadPtrHandle<ServiceWorker> aServiceWorker,
                  InternalResponse* aInternalResponse,
                  const ChannelInfo& aWorkerChannelInfo)
     : mChannel(aChannel)
+    , mServiceWorker(aServiceWorker)
     , mInternalResponse(aInternalResponse)
     , mWorkerChannelInfo(aWorkerChannelInfo)
   {
@@ -121,6 +128,11 @@ public:
   {
     AssertIsOnMainThread();
 
+    if (!CSPPermitsResponse()) {
+      mChannel->Cancel(NS_ERROR_CONTENT_BLOCKED);
+      return NS_OK;
+    }
+
     ChannelInfo channelInfo;
     if (mInternalResponse->GetChannelInfo().IsInitialized()) {
       channelInfo = mInternalResponse->GetChannelInfo();
@@ -147,6 +159,34 @@ public:
     NS_WARN_IF_FALSE(NS_SUCCEEDED(rv), "Failed to finish synthesized response");
     return rv;
   }
+
+  bool CSPPermitsResponse()
+  {
+    AssertIsOnMainThread();
+
+    nsresult rv;
+    nsCOMPtr<nsIURI> uri;
+    nsAutoCString url;
+    mInternalResponse->GetUnfilteredUrl(url);
+    if (url.IsEmpty()) {
+      // Synthetic response. The buck stops at the worker script.
+      url = mServiceWorker->Info()->ScriptSpec();
+    }
+    rv = NS_NewURI(getter_AddRefs(uri), url, nullptr, nullptr);
+    NS_ENSURE_SUCCESS(rv, false);
+
+    nsCOMPtr<nsIChannel> underlyingChannel;
+    rv = mChannel->GetChannel(getter_AddRefs(underlyingChannel));
+    NS_ENSURE_SUCCESS(rv, false);
+    NS_ENSURE_TRUE(underlyingChannel, false);
+    nsCOMPtr<nsILoadInfo> loadInfo = underlyingChannel->GetLoadInfo();
+
+    int16_t decision = nsIContentPolicy::ACCEPT;
+    rv = NS_CheckContentLoadPolicy(loadInfo->InternalContentPolicyType(), uri, loadInfo->LoadingPrincipal(),
+                                   loadInfo->LoadingNode(), EmptyCString(), nullptr, &decision);
+    NS_ENSURE_SUCCESS(rv, false);
+    return decision == nsIContentPolicy::ACCEPT;
+  }
 };
 
 class RespondWithHandler final : public PromiseNativeHandler
@@ -183,13 +223,16 @@ private:
 struct RespondWithClosure
 {
   nsMainThreadPtrHandle<nsIInterceptedChannel> mInterceptedChannel;
+  nsMainThreadPtrHandle<ServiceWorker> mServiceWorker;
   nsRefPtr<InternalResponse> mInternalResponse;
   ChannelInfo mWorkerChannelInfo;
 
   RespondWithClosure(nsMainThreadPtrHandle<nsIInterceptedChannel>& aChannel,
+                     nsMainThreadPtrHandle<ServiceWorker>& aServiceWorker,
                      InternalResponse* aInternalResponse,
                      const ChannelInfo& aWorkerChannelInfo)
     : mInterceptedChannel(aChannel)
+    , mServiceWorker(aServiceWorker)
     , mInternalResponse(aInternalResponse)
     , mWorkerChannelInfo(aWorkerChannelInfo)
   {
@@ -202,6 +245,7 @@ void RespondWithCopyComplete(void* aClosure, nsresult aStatus)
   nsCOMPtr<nsIRunnable> event;
   if (NS_SUCCEEDED(aStatus)) {
     event = new FinishResponse(data->mInterceptedChannel,
+                               data->mServiceWorker,
                                data->mInternalResponse,
                                data->mWorkerChannelInfo);
   } else {
@@ -307,7 +351,7 @@ RespondWithHandler::ResolvedCallback(JSContext* aCx, JS::Handle<JS::Value> aValu
   }
 
   nsAutoPtr<RespondWithClosure> closure(
-      new RespondWithClosure(mInterceptedChannel, ir, worker->GetChannelInfo()));
+      new RespondWithClosure(mInterceptedChannel, mServiceWorker, ir, worker->GetChannelInfo()));
   nsCOMPtr<nsIInputStream> body;
   ir->GetUnfilteredBody(getter_AddRefs(body));
   // Errors and redirects may not have a body.
diff --git a/testing/web-platform/mozilla/meta/service-workers/service-worker/fetch-csp.https.html.ini b/testing/web-platform/mozilla/meta/service-workers/service-worker/fetch-csp.https.html.ini
deleted file mode 100644
index d203be567b75..000000000000
--- a/testing/web-platform/mozilla/meta/service-workers/service-worker/fetch-csp.https.html.ini
+++ /dev/null
@@ -1,5 +0,0 @@
-[fetch-csp.https.html]
-  type: testharness
-  [Verify CSP control of fetch() in a Service Worker]
-    expected: FAIL
-
diff --git a/testing/web-platform/mozilla/tests/service-workers/service-worker/resources/fetch-csp-iframe.html b/testing/web-platform/mozilla/tests/service-workers/service-worker/resources/fetch-csp-iframe.html
index c6b3e022eaf7..cf7175bc83df 100644
--- a/testing/web-platform/mozilla/tests/service-workers/service-worker/resources/fetch-csp-iframe.html
+++ b/testing/web-platform/mozilla/tests/service-workers/service-worker/resources/fetch-csp-iframe.html
@@ -6,12 +6,6 @@ var host_info = get_host_info();
 var results = '';
 var port = undefined;
 
-var meta = document.createElement('meta');
-meta.setAttribute('http-equiv', 'Content-Security-Policy');
-meta.setAttribute('content', 'img-src ' + host_info['HTTPS_ORIGIN'] +
-                  '; script-src \'unsafe-inline\'');
-document.head.appendChild(meta);
-
 function test1() {
   var img = document.createElement('img');
   document.body.appendChild(img);
diff --git a/testing/web-platform/mozilla/tests/service-workers/service-worker/resources/fetch-csp-iframe.html.sub.headers b/testing/web-platform/mozilla/tests/service-workers/service-worker/resources/fetch-csp-iframe.html.sub.headers
new file mode 100644
index 000000000000..300efe049b5d
--- /dev/null
+++ b/testing/web-platform/mozilla/tests/service-workers/service-worker/resources/fetch-csp-iframe.html.sub.headers
@@ -0,0 +1 @@
+Content-Security-Policy: img-src https://{{host}}:{{ports[https][0]}}