diff --git a/.gopmfile b/.gopmfile
index 3ba514afc..7b1bf3091 100644
--- a/.gopmfile
+++ b/.gopmfile
@@ -24,6 +24,7 @@ github.com/macaron-contrib/session =
 github.com/macaron-contrib/toolbox = commit:57127bcc89
 github.com/mattn/go-sqlite3 = commit:a80c27ba33
 github.com/nfnt/resize = commit:581d15cb53
+github.com/russross/blackfriday = 
 github.com/saintfish/chardet = commit:3af4cd4741
 
 [res]
diff --git a/gogs.go b/gogs.go
index 289ad1912..12f142aba 100644
--- a/gogs.go
+++ b/gogs.go
@@ -17,7 +17,7 @@ import (
 	"github.com/gogits/gogs/modules/setting"
 )
 
-const APP_VER = "0.5.4.1003 Beta"
+const APP_VER = "0.5.4.1004 Beta"
 
 func init() {
 	runtime.GOMAXPROCS(runtime.NumCPU())
diff --git a/models/repo.go b/models/repo.go
index a79c2491c..8e29b3357 100644
--- a/models/repo.go
+++ b/models/repo.go
@@ -23,6 +23,7 @@ import (
 	"github.com/Unknwon/cae/zip"
 	"github.com/Unknwon/com"
 
+	"github.com/gogits/gogs/modules/base"
 	"github.com/gogits/gogs/modules/git"
 	"github.com/gogits/gogs/modules/log"
 	"github.com/gogits/gogs/modules/process"
@@ -48,7 +49,7 @@ var (
 )
 
 var (
-	DescriptionPattern = regexp.MustCompile(`https?://\S+`)
+	DescPattern = regexp.MustCompile(`https?://\S+`)
 )
 
 func LoadRepoConfig() {
@@ -181,7 +182,7 @@ func (repo *Repository) DescriptionHtml() template.HTML {
 		ss := html.EscapeString(s)
 		return fmt.Sprintf(`<a href="%s" target="_blank">%s</a>`, ss, ss)
 	}
-	return template.HTML(DescriptionPattern.ReplaceAllStringFunc(repo.Description, sanitize))
+	return template.HTML(DescPattern.ReplaceAllStringFunc(base.XSSString(repo.Description), sanitize))
 }
 
 // IsRepositoryExist returns true if the repository with given name under user has already existed.
diff --git a/modules/base/markdown.go b/modules/base/markdown.go
index a3db15df1..cb0832009 100644
--- a/modules/base/markdown.go
+++ b/modules/base/markdown.go
@@ -13,7 +13,8 @@ import (
 	"regexp"
 	"strings"
 
-	"github.com/gogits/gfm"
+	"github.com/russross/blackfriday"
+
 	"github.com/gogits/gogs/modules/setting"
 )
 
@@ -74,7 +75,7 @@ func IsReadmeFile(name string) bool {
 }
 
 type CustomRender struct {
-	gfm.Renderer
+	blackfriday.Renderer
 	urlPrefix string
 }
 
@@ -154,39 +155,40 @@ func RenderSpecialLink(rawBytes []byte, urlPrefix string) []byte {
 
 func RenderRawMarkdown(body []byte, urlPrefix string) []byte {
 	htmlFlags := 0
-	// htmlFlags |= gfm.HTML_USE_XHTML
-	// htmlFlags |= gfm.HTML_USE_SMARTYPANTS
-	// htmlFlags |= gfm.HTML_SMARTYPANTS_FRACTIONS
-	// htmlFlags |= gfm.HTML_SMARTYPANTS_LATEX_DASHES
-	// htmlFlags |= gfm.HTML_SKIP_HTML
-	htmlFlags |= gfm.HTML_SKIP_STYLE
-	htmlFlags |= gfm.HTML_SKIP_SCRIPT
-	htmlFlags |= gfm.HTML_GITHUB_BLOCKCODE
-	htmlFlags |= gfm.HTML_OMIT_CONTENTS
-	// htmlFlags |= gfm.HTML_COMPLETE_PAGE
+	// htmlFlags |= blackfriday.HTML_USE_XHTML
+	// htmlFlags |= blackfriday.HTML_USE_SMARTYPANTS
+	// htmlFlags |= blackfriday.HTML_SMARTYPANTS_FRACTIONS
+	// htmlFlags |= blackfriday.HTML_SMARTYPANTS_LATEX_DASHES
+	// htmlFlags |= blackfriday.HTML_SKIP_HTML
+	htmlFlags |= blackfriday.HTML_SKIP_STYLE
+	// htmlFlags |= blackfriday.HTML_SKIP_SCRIPT
+	// htmlFlags |= blackfriday.HTML_GITHUB_BLOCKCODE
+	htmlFlags |= blackfriday.HTML_OMIT_CONTENTS
+	// htmlFlags |= blackfriday.HTML_COMPLETE_PAGE
 	renderer := &CustomRender{
-		Renderer:  gfm.HtmlRenderer(htmlFlags, "", ""),
+		Renderer:  blackfriday.HtmlRenderer(htmlFlags, "", ""),
 		urlPrefix: urlPrefix,
 	}
 
 	// set up the parser
 	extensions := 0
-	extensions |= gfm.EXTENSION_NO_INTRA_EMPHASIS
-	extensions |= gfm.EXTENSION_TABLES
-	extensions |= gfm.EXTENSION_FENCED_CODE
-	extensions |= gfm.EXTENSION_AUTOLINK
-	extensions |= gfm.EXTENSION_STRIKETHROUGH
-	extensions |= gfm.EXTENSION_HARD_LINE_BREAK
-	extensions |= gfm.EXTENSION_SPACE_HEADERS
-	extensions |= gfm.EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK
-
-	body = gfm.Markdown(body, renderer, extensions)
+	extensions |= blackfriday.EXTENSION_NO_INTRA_EMPHASIS
+	extensions |= blackfriday.EXTENSION_TABLES
+	extensions |= blackfriday.EXTENSION_FENCED_CODE
+	extensions |= blackfriday.EXTENSION_AUTOLINK
+	extensions |= blackfriday.EXTENSION_STRIKETHROUGH
+	extensions |= blackfriday.EXTENSION_HARD_LINE_BREAK
+	extensions |= blackfriday.EXTENSION_SPACE_HEADERS
+	extensions |= blackfriday.EXTENSION_NO_EMPTY_LINE_BEFORE_BLOCK
+
+	body = blackfriday.Markdown(body, renderer, extensions)
 	return body
 }
 
 func RenderMarkdown(rawBytes []byte, urlPrefix string) []byte {
 	body := RenderSpecialLink(rawBytes, urlPrefix)
 	body = RenderRawMarkdown(body, urlPrefix)
+	body = XSS(body)
 	return body
 }
 
diff --git a/modules/base/tool.go b/modules/base/tool.go
index b4083d090..38fd1e21e 100644
--- a/modules/base/tool.go
+++ b/modules/base/tool.go
@@ -14,6 +14,7 @@ import (
 	"hash"
 	"html/template"
 	"math"
+	"regexp"
 	"strings"
 	"time"
 
@@ -446,3 +447,29 @@ func DateFormat(t time.Time, format string) string {
 	format = replacer.Replace(format)
 	return t.Format(format)
 }
+
+type xssFilter struct {
+	reg  *regexp.Regexp
+	repl []byte
+}
+
+var (
+	whiteSpace = []byte(" ")
+	xssFilters = []xssFilter{
+		{regexp.MustCompile(`\ [ONon]\w*=["]*`), whiteSpace},
+		{regexp.MustCompile(`<[SCRIPTscript]{6}`), whiteSpace},
+		{regexp.MustCompile(`=[` + "`" + `'"]*[JAVASCRIPTjavascript \t\0&#x0D;]*:`), whiteSpace},
+	}
+)
+
+// XSS goes through all the XSS filters to make user input content as safe as possible.
+func XSS(in []byte) []byte {
+	for _, filter := range xssFilters {
+		in = filter.reg.ReplaceAll(in, filter.repl)
+	}
+	return in
+}
+
+func XSSString(in string) string {
+	return string(XSS([]byte(in)))
+}
diff --git a/templates/.VERSION b/templates/.VERSION
index 24a40ce35..776ae02a1 100644
--- a/templates/.VERSION
+++ b/templates/.VERSION
@@ -1 +1 @@
-0.5.4.1003 Beta
\ No newline at end of file
+0.5.4.1004 Beta
\ No newline at end of file