diff --git a/public/res/eventMgr.js b/public/res/eventMgr.js
index ab0adcbf..f90aa57e 100644
--- a/public/res/eventMgr.js
+++ b/public/res/eventMgr.js
@@ -24,8 +24,8 @@ define([
     "extensions/documentManager",
     "extensions/workingIndicator",
     "extensions/notifications",
+	"extensions/umlDiagrams",
     "extensions/markdownExtra",
-    "extensions/umlDiagrams",
     "extensions/toc",
     "extensions/mathJax",
     "extensions/emailConverter",
@@ -39,8 +39,9 @@ define([
     "extensions/shortcuts",
     "extensions/userCustom",
     "extensions/comments",
+    "extensions/htmlSanitizer",
     "bootstrap",
-    "jquery-waitforimages",
+    "jquery-waitforimages"
 ], function($, _, crel, utils, logger, Extension, settings, settingsExtensionsAccordionHTML) {
 
     var eventMgr = {};
diff --git a/public/res/extensions/htmlSanitizer.js b/public/res/extensions/htmlSanitizer.js
new file mode 100644
index 00000000..e34b4afa
--- /dev/null
+++ b/public/res/extensions/htmlSanitizer.js
@@ -0,0 +1,395 @@
+define([
+	"jquery",
+	"underscore",
+	"utils",
+	"logger",
+	"classes/Extension",
+	"text!html/htmlSanitizerSettingsBlock.html"
+], function($, _, utils, logger, Extension, htmlSanitizerSettingsBlockHTML) {
+
+	var htmlSanitizer = new Extension("htmlSanitizer", "HTML Sanitizer", true);
+	htmlSanitizer.settingsBlock = htmlSanitizerSettingsBlockHTML;
+
+	var buf;
+	htmlSanitizer.onPagedownConfigure = function(editor) {
+		var converter = editor.getConverter();
+		converter.hooks.chain("postConversion", function(html) {
+			buf = [];
+			html.split('<div class="se-preview-section-delimiter"></div>').forEach(function(sectionHtml) {
+				try {
+					htmlParser(sectionHtml, htmlSanitizeWriter(buf, function(uri, isImage) {
+						return !/^unsafe/.test(sanitizeUri(uri, isImage));
+					}));
+				}
+				catch(e) {
+				}
+				buf.push('<div class="se-preview-section-delimiter"></div>');
+			});
+			return buf.slice(0, -1).join('');
+		});
+	};
+
+	/**
+	 * @license AngularJS v1.2.16
+	 * (c) 2010-2014 Google, Inc. http://angularjs.org
+	 * License: MIT
+	 */
+
+	var aHrefSanitizationWhitelist = /^\s*(https?|ftp|mailto|tel|file):/,
+		imgSrcSanitizationWhitelist = /^\s*(https?|ftp|file):|data:image\//;
+
+	function sanitizeUri(uri, isImage) {
+		var regex = isImage ? imgSrcSanitizationWhitelist : aHrefSanitizationWhitelist;
+		var normalizedVal;
+		normalizedVal = utils.urlResolve(uri).href;
+		if(normalizedVal !== '' && !normalizedVal.match(regex)) {
+			return 'unsafe:' + normalizedVal;
+		}
+	}
+
+	// Regular Expressions for parsing tags and attributes
+	var START_TAG_REGEXP =
+			/^<\s*([\w:-]+)((?:\s+[\w:-]+(?:\s*=\s*(?:(?:"[^"]*")|(?:'[^']*')|[^>\s]+))?)*)\s*(\/?)\s*>/,
+		END_TAG_REGEXP = /^<\s*\/\s*([\w:-]+)[^>]*>/,
+		ATTR_REGEXP = /([\w:-]+)(?:\s*=\s*(?:(?:"((?:[^"])*)")|(?:'((?:[^'])*)')|([^>\s]+)))?/g,
+		BEGIN_TAG_REGEXP = /^</,
+		BEGING_END_TAGE_REGEXP = /^<\s*\//,
+		COMMENT_REGEXP = /<!--(.*?)-->/g,
+		DOCTYPE_REGEXP = /<!DOCTYPE([^>]*?)>/i,
+		CDATA_REGEXP = /<!\[CDATA\[(.*?)]]>/g,
+		// Match everything outside of normal chars and " (quote character)
+		NON_ALPHANUMERIC_REGEXP = /([^\#-~| |!])/g;
+
+	function makeMap(str) {
+		var obj = {}, items = str.split(','), i;
+		for(i = 0; i < items.length; i++) {
+			obj[items[i]] = true;
+		}
+		return obj;
+	}
+
+	// Good source of info about elements and attributes
+	// http://dev.w3.org/html5/spec/Overview.html#semantics
+	// http://simon.html5.org/html-elements
+
+	// Safe Void Elements - HTML5
+	// http://dev.w3.org/html5/spec/Overview.html#void-elements
+	var voidElements = makeMap("area,br,col,hr,img,wbr");
+
+	// Elements that you can, intentionally, leave open (and which close themselves)
+	// http://dev.w3.org/html5/spec/Overview.html#optional-tags
+	var optionalEndTagBlockElements = makeMap("colgroup,dd,dt,li,p,tbody,td,tfoot,th,thead,tr"),
+		optionalEndTagInlineElements = makeMap("rp,rt"),
+		optionalEndTagElements = _.extend({},
+			optionalEndTagInlineElements,
+			optionalEndTagBlockElements);
+
+	// Safe Block Elements - HTML5
+	var blockElements = _.extend({}, optionalEndTagBlockElements, makeMap("address,article," +
+		"aside,blockquote,caption,center,del,dir,div,dl,figure,figcaption,footer,h1,h2,h3,h4,h5," +
+		"h6,header,hgroup,hr,ins,map,menu,nav,ol,pre,script,section,table,ul"));
+
+	// Inline Elements - HTML5
+	var inlineElements = _.extend({}, optionalEndTagInlineElements, makeMap("a,abbr,acronym,b," +
+		"bdi,bdo,big,br,cite,code,del,dfn,em,font,i,img,ins,kbd,label,map,mark,q,ruby,rp,rt,s," +
+		"samp,small,span,strike,strong,sub,sup,time,tt,u,var"));
+
+
+	// Special Elements (can contain anything)
+	var specialElements = makeMap("script,style");
+
+	var validElements = _.extend({},
+		voidElements,
+		blockElements,
+		inlineElements,
+		optionalEndTagElements);
+
+	//Attributes that have href and hence need to be sanitized
+	var uriAttrs = makeMap("background,cite,href,longdesc,src,usemap");
+	var validAttrs = _.extend({}, uriAttrs, makeMap(
+			'abbr,align,alt,axis,bgcolor,border,cellpadding,cellspacing,class,clear,' +
+			'color,cols,colspan,compact,coords,dir,face,headers,height,hreflang,hspace,' +
+			'ismap,lang,language,nohref,nowrap,rel,rev,rows,rowspan,rules,' +
+			'scope,scrolling,shape,size,span,start,summary,target,title,type,' +
+			'valign,value,vspace,width'));
+
+	// benweet: Add id
+	validAttrs.id = true;
+
+	/*
+	 * HTML Parser By Misko Hevery (misko@hevery.com)
+	 * based on:  HTML Parser By John Resig (ejohn.org)
+	 * Original code by Erik Arvidsson, Mozilla Public License
+	 * http://erik.eae.net/simplehtmlparser/simplehtmlparser.js
+	 *
+	 * // Use like so:
+	 * htmlParser(htmlString, {
+	 *     start: function(tag, attrs, unary) {},
+	 *     end: function(tag) {},
+	 *     chars: function(text) {},
+	 *     comment: function(text) {}
+	 * });
+	 *
+	 */
+	/* jshint -W083 */
+	function htmlParser(html, handler) {
+		var index, chars, match, stack = [], last = html;
+		stack.last = function() {
+			return stack[ stack.length - 1 ];
+		};
+
+		function parseStartTag(tag, tagName, rest, unary) {
+			tagName = tagName && tagName.toLowerCase();
+			if(blockElements[ tagName ]) {
+				while(stack.last() && inlineElements[ stack.last() ]) {
+					parseEndTag("", stack.last());
+				}
+			}
+
+			if(optionalEndTagElements[ tagName ] && stack.last() == tagName) {
+				parseEndTag("", tagName);
+			}
+
+			unary = voidElements[ tagName ] || !!unary;
+
+			if(!unary) {
+				stack.push(tagName);
+			}
+
+			var attrs = {};
+
+			rest.replace(ATTR_REGEXP,
+				function(match, name, doubleQuotedValue, singleQuotedValue, unquotedValue) {
+					var value = doubleQuotedValue ||
+						singleQuotedValue ||
+						unquotedValue ||
+						'';
+
+					attrs[name] = decodeEntities(value);
+				});
+			if(handler.start) {
+				handler.start(tagName, attrs, unary);
+			}
+		}
+
+		function parseEndTag(tag, tagName) {
+			var pos = 0, i;
+			tagName = tagName && tagName.toLowerCase();
+			if(tagName) {
+				// Find the closest opened tag of the same type
+				for(pos = stack.length - 1; pos >= 0; pos--) {
+					if(stack[ pos ] == tagName) {
+						break;
+					}
+				}
+			}
+
+			if(pos >= 0) {
+				// Close all the open elements, up the stack
+				for(i = stack.length - 1; i >= pos; i--) {
+					if(handler.end) {
+						handler.end(stack[ i ]);
+					}
+				}
+
+				// Remove the open elements from the stack
+				stack.length = pos;
+			}
+		}
+
+		while(html) {
+			chars = true;
+
+			// Make sure we're not in a script or style element
+			if(!stack.last() || !specialElements[ stack.last() ]) {
+
+				// Comment
+				if(html.indexOf("<!--") === 0) {
+					// comments containing -- are not allowed unless they terminate the comment
+					index = html.indexOf("--", 4);
+
+					if(index >= 0 && html.lastIndexOf("-->", index) === index) {
+						if(handler.comment) {
+							handler.comment(html.substring(4, index));
+						}
+						html = html.substring(index + 3);
+						chars = false;
+					}
+					// DOCTYPE
+				} else if(DOCTYPE_REGEXP.test(html)) {
+					match = html.match(DOCTYPE_REGEXP);
+
+					if(match) {
+						html = html.replace(match[0], '');
+						chars = false;
+					}
+					// end tag
+				} else if(BEGING_END_TAGE_REGEXP.test(html)) {
+					match = html.match(END_TAG_REGEXP);
+
+					if(match) {
+						html = html.substring(match[0].length);
+						match[0].replace(END_TAG_REGEXP, parseEndTag);
+						chars = false;
+					}
+
+					// start tag
+				} else if(BEGIN_TAG_REGEXP.test(html)) {
+					match = html.match(START_TAG_REGEXP);
+
+					if(match) {
+						html = html.substring(match[0].length);
+						match[0].replace(START_TAG_REGEXP, parseStartTag);
+						chars = false;
+					}
+				}
+
+				if(chars) {
+					index = html.indexOf("<");
+
+					var text = index < 0 ? html : html.substring(0, index);
+					html = index < 0 ? "" : html.substring(index);
+
+					if(handler.chars) {
+						handler.chars(decodeEntities(text));
+					}
+				}
+
+			} else {
+				html = html.replace(new RegExp("(.*)<\\s*\\/\\s*" + stack.last() + "[^>]*>", 'i'),
+					function(all, text) {
+						text = text.replace(COMMENT_REGEXP, "$1").replace(CDATA_REGEXP, "$1");
+
+						if(handler.chars) {
+							handler.chars(decodeEntities(text));
+						}
+
+						return "";
+					});
+
+				parseEndTag("", stack.last());
+			}
+
+			if(html == last) {
+				//throw new Error("The sanitizer was unable to parse the following block of html: " + html);
+				stack.reverse();
+				return stack.forEach(function(tag) {
+					buf.push('</');
+					buf.push(tag);
+					buf.push('>');
+				});
+			}
+			last = html;
+		}
+
+		// Clean up any remaining tags
+		parseEndTag();
+	}
+
+	var hiddenPre = document.createElement("pre");
+	var spaceRe = /^(\s*)([\s\S]*?)(\s*)$/;
+
+	/**
+	 * decodes all entities into regular string
+	 * @param value
+	 * @returns {string} A string with decoded entities.
+	 */
+	function decodeEntities(value) {
+		if(!value) {
+			return '';
+		}
+
+		// Note: IE8 does not preserve spaces at the start/end of innerHTML
+		// so we must capture them and reattach them afterward
+		var parts = spaceRe.exec(value);
+		var spaceBefore = parts[1];
+		var spaceAfter = parts[3];
+		var content = parts[2];
+		if(content) {
+			hiddenPre.innerHTML = content.replace(/</g, "&lt;");
+			// innerText depends on styling as it doesn't display hidden elements.
+			// Therefore, it's better to use textContent not to cause unnecessary
+			// reflows. However, IE<9 don't support textContent so the innerText
+			// fallback is necessary.
+			content = 'textContent' in hiddenPre ?
+				hiddenPre.textContent : hiddenPre.innerText;
+		}
+		return spaceBefore + content + spaceAfter;
+	}
+
+	/**
+	 * Escapes all potentially dangerous characters, so that the
+	 * resulting string can be safely inserted into attribute or
+	 * element text.
+	 * @param value
+	 * @returns {string} escaped text
+	 */
+	function encodeEntities(value) {
+		return value.
+			replace(/&/g, '&amp;').
+			replace(NON_ALPHANUMERIC_REGEXP, function(value) {
+				return '&#' + value.charCodeAt(0) + ';';
+			}).
+			replace(/</g, '&lt;').
+			replace(/>/g, '&gt;');
+	}
+
+
+	/**
+	 * create an HTML/XML writer which writes to buffer
+	 * @param {Array} buf use buf.jain('') to get out sanitized html string
+	 * @returns {object} in the form of {
+	 *     start: function(tag, attrs, unary) {},
+	 *     end: function(tag) {},
+	 *     chars: function(text) {},
+	 *     comment: function(text) {}
+	 * }
+	 */
+	function htmlSanitizeWriter(buf, uriValidator) {
+		var ignore = false;
+		var out = _.bind(buf.push, buf);
+		return {
+			start: function(tag, attrs, unary) {
+				tag = tag && tag.toLowerCase();
+				if(!ignore && specialElements[tag]) {
+					ignore = tag;
+				}
+				if(!ignore && validElements[tag] === true) {
+					out('<');
+					out(tag);
+					_.forEach(attrs, function(value, key) {
+						var lkey = key && key.toLowerCase();
+						var isImage = (tag === 'img' && lkey === 'src') || (lkey === 'background');
+						if(validAttrs[lkey] === true &&
+							(uriAttrs[lkey] !== true || uriValidator(value, isImage))) {
+							out(' ');
+							out(key);
+							out('="');
+							out(encodeEntities(value));
+							out('"');
+						}
+					});
+					out(unary ? '/>' : '>');
+				}
+			},
+			end: function(tag) {
+				tag = tag && tag.toLowerCase();
+				if(!ignore && validElements[tag] === true) {
+					out('</');
+					out(tag);
+					out('>');
+				}
+				if(tag == ignore) {
+					ignore = false;
+				}
+			},
+			chars: function(chars) {
+				if(!ignore) {
+					out(encodeEntities(chars));
+				}
+			}
+		};
+	}
+
+	return htmlSanitizer;
+});
\ No newline at end of file
diff --git a/public/res/html/htmlSanitizerSettingsBlock.html b/public/res/html/htmlSanitizerSettingsBlock.html
new file mode 100644
index 00000000..2fea440f
--- /dev/null
+++ b/public/res/html/htmlSanitizerSettingsBlock.html
@@ -0,0 +1,2 @@
+<p>Prevents cross-site-scripting attacks (XSS).</p>
+<p class="alert alert-danger"><i class="icon-attention"></i> <b>Careful:</b> Disable at your own risk!</p>