fix: xss vulnerability (#244)

Author: fsbraun

djangocms_frontend/templates/djangocms_frontend.html

@@ -8,7 +8,7 @@
             {% block meta %}
                 <meta name="description" content="{% page_attribute meta_description %}"/>
                 <meta property="og:type" content="website"/>
-                <meta property="og:title" content="{% page_attribute "page_title" %}"/>
+                <meta property="og:title" content="{{ request.current_page.get_page_title|escape }}"/>
                 <meta property="og:description" content="{% page_attribute meta_description %}"/>
             {% endblock meta %}
             {% block canonical_url %}