Index: notebook-4.2.0/notebook/static/notebook/js/outputarea.js
===================================================================
--- notebook-4.2.0/notebook/static/notebook/js/outputarea.js
+++ notebook-4.2.0/notebook/static/notebook/js/outputarea.js	2018-03-18 20:00:55.135031081 +0100
@@ -554,16 +554,21 @@
             var type = OutputArea.display_order[i];
             var append = OutputArea.append_map[type];
             if ((json.data[type] !== undefined) && append) {
+		var md = json.metadata || {};
                 var value = json.data[type];
+		var toinsert;
                 if (!this.trusted && !OutputArea.safe_outputs[type]) {
                     // not trusted, sanitize HTML
                     if (type==='text/html' || type==='text/svg') {
-                        value = security.sanitize_html(value);
+                        var parsed = $(security.sanitize_html_and_parse(value));
+			toinsert = append.apply(this, [parsed, md, element, handle_inserted]);
                     } else {
                         // don't display if we don't know how to sanitize it
                         console.log("Ignoring untrusted " + type + " output.");
                         continue;
                     }
+		} else {
+		    toinsert = append.apply(this, [value, md, element, handle_inserted]);
                 }
                 var md = json.metadata || {};
                 var toinsert = append.apply(this, [value, md, element, handle_inserted]);
Index: notebook-4.2.0/notebook/static/notebook/js/textcell.js
===================================================================
--- notebook-4.2.0/notebook/static/notebook/js/textcell.js
+++ notebook-4.2.0/notebook/static/notebook/js/textcell.js	2018-03-18 20:04:04.846222930 +0100
@@ -274,8 +274,7 @@
             math = text_and_math[1];
             marked(text, function (err, html) {
                 html = mathjaxutils.replace_math(html, math);
-                html = security.sanitize_html(html);
-                html = $($.parseHTML(html));
+		html = $(security.sanitize_html_and_parse(html));
                 // add anchors to headings
                 html.find(":header").addBack(":header").each(function (i, h) {
                     h = $(h);
Index: notebook-4.2.0/notebook/static/base/js/security.js
===================================================================
--- notebook-4.2.0/notebook/static/base/js/security.js
+++ notebook-4.2.0/notebook/static/base/js/security.js	2018-03-18 19:58:13.814017593 +0100
@@ -115,10 +115,30 @@
         }
         
         return sanitized;
+
+        var sanitize_html_and_parse = function (html, allow_css) {
+            /**
+             * Sanitize HTML and parse it safely using jQuery.
+             *
+             * This disable's jQuery's html 'prefilter', which can make invalid
+             * HTML valid after the sanitizer has checked it.
+             *
+             * Returns an array of DOM nodes.
+             */
+            var sanitized_html = sanitize_html(html, allow_css);
+            var prev_htmlPrefilter = $.htmlPrefilter;
+            $.htmlPrefilter = function(html) {return html;};  // Don't modify HTML
+            try {
+                return $.parseHTML(sanitized_html);
+            } finally {
+                $.htmlPrefilter = prev_htmlPrefilter;  // Set it back again
+            }
+        };
     };
     
     var security = {
         caja: caja,
+	sanitize_html_and_parse: sanitize_html_and_parse,
         sanitize_html: sanitize_html
     };