diff --git a/dom/html/nsHTMLDocument.cpp b/dom/html/nsHTMLDocument.cpp
index 9116dfad082e..74edafe6546c 100644
--- a/dom/html/nsHTMLDocument.cpp
+++ b/dom/html/nsHTMLDocument.cpp
@@ -3534,6 +3534,14 @@ nsHTMLDocument::QueryCommandSupported(const nsAString & commandID,
 bool
 nsHTMLDocument::QueryCommandSupported(const nsAString& commandID)
 {
+  // Gecko technically supports the paste command, but non-privileged content
+  // will be unable to call it. For that reason, we report that paste is
+  // not supported to this non-privileged content (as it effectively is).
+  bool restricted = commandID.LowerCaseEqualsLiteral("paste");
+  if (restricted && !nsContentUtils::IsCallerChrome()) {
+    return false;
+  }
+
   // commandID is supported if it can be converted to a Midas command
   nsAutoCString cmdToDispatch;
   return ConvertToMidasInternalCommand(commandID, cmdToDispatch);
diff --git a/dom/tests/mochitest/general/mochitest.ini b/dom/tests/mochitest/general/mochitest.ini
index a9c9a9579280..d1368823c964 100644
--- a/dom/tests/mochitest/general/mochitest.ini
+++ b/dom/tests/mochitest/general/mochitest.ini
@@ -100,3 +100,4 @@ skip-if = (buildapp == 'b2g' && toolkit != 'gonk') #Bug 931116, b2g desktop spec
 skip-if = (buildapp == 'b2g' && toolkit != 'gonk') #Bug 931116, b2g desktop specific, initial triage
 [test_navigation_timing.html]
 skip-if = buildapp == 'b2g' || buildapp == 'mulet'
+[test_bug1161721.html]
diff --git a/dom/tests/mochitest/general/test_bug1161721.html b/dom/tests/mochitest/general/test_bug1161721.html
new file mode 100644
index 000000000000..3e59dd81b637
--- /dev/null
+++ b/dom/tests/mochitest/general/test_bug1161721.html
@@ -0,0 +1,32 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1161721
+-->
+<head>
+  <title>Test for Bug 1161721</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/EventUtils.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/WindowSnapshot.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1161721">Mozilla Bug 1161721</a>
+<p id="display"></p>
+
+<div id="content">
+</div>
+
+<pre id="test">
+  <script type="application/javascript">
+    ok(!document.queryCommandSupported("paste"), "Paste isn't supported in non-privilged JavaScript");
+    ok(document.queryCommandSupported("copy"), "Copy is supported in non-privilged JavaScript");
+    ok(document.queryCommandSupported("cut"), "Cut is supported in non-privilged JavaScript");
+
+    ok(SpecialPowers.wrap(document).queryCommandSupported("paste"), "Paste is supported in privilged JavaScript");
+    ok(SpecialPowers.wrap(document).queryCommandSupported("copy"), "Copy is supported in privilged JavaScript");
+    ok(SpecialPowers.wrap(document).queryCommandSupported("cut"), "Cut is supported in privilged JavaScript");
+  </script>
+</pre>
+</body>
+</html>
diff --git a/editor/libeditor/tests/browserscope/lib/richtext2/currentStatus.js b/editor/libeditor/tests/browserscope/lib/richtext2/currentStatus.js
index b8d145b08d7b..570587e208d6 100644
--- a/editor/libeditor/tests/browserscope/lib/richtext2/currentStatus.js
+++ b/editor/libeditor/tests/browserscope/lib/richtext2/currentStatus.js
@@ -289,6 +289,9 @@ const knownFailures = {
     "Q-Proposed-UNBOOKMARK_TEXT-1-dM": true,
     "Q-Proposed-UNBOOKMARK_TEXT-1-body": true,
     "Q-Proposed-UNBOOKMARK_TEXT-1-div": true,
+    "Q-Proposed-PASTE_TEXT-1-dM": true,
+    "Q-Proposed-PASTE_TEXT-1-body": true,
+    "Q-Proposed-PASTE_TEXT-1-div": true,
     "QE-Proposed-UNSELECT_TEXT-1-dM": true,
     "QE-Proposed-UNSELECT_TEXT-1-body": true,
     "QE-Proposed-UNSELECT_TEXT-1-div": true,
