diff --git a/conf/tests.py b/conf/tests.py
index f6debd6..55f4853 100644
--- a/conf/tests.py
+++ b/conf/tests.py
@@ -66,10 +66,11 @@ class WebsiteConfigAPITest(APITestCase):
         self.create_super_admin()
         url = self.reverse("website_config_api")
         data = {"website_base_url": "http://test.com", "website_name": "test name",
-                "website_name_shortcut": "test oj", "website_footer": "<a>test</a>",
+                "website_name_shortcut": "test oj", "website_footer": "<img onerror=alert(1) src=#>",
                 "allow_register": True, "submission_list_show_all": False}
         resp = self.client.post(url, data=data)
         self.assertSuccess(resp)
+        self.assertEqual(SysOptions.website_footer, "<img src=\"#\" />")
 
     def test_get_website_config(self):
         # do not need to login
diff --git a/conf/views.py b/conf/views.py
index a4f070c..b4e47bb 100644
--- a/conf/views.py
+++ b/conf/views.py
@@ -13,6 +13,7 @@ from judge.languages import languages, spj_languages
 from options.options import SysOptions
 from utils.api import APIView, CSRFExemptAPIView, validate_serializer
 from utils.shortcuts import send_email
+from utils.xss_filter import XSSHtml
 from .models import JudgeServer
 from .serializers import (CreateEditWebsiteConfigSerializer,
                           CreateSMTPConfigSerializer, EditSMTPConfigSerializer,
@@ -84,6 +85,9 @@ class WebsiteConfigAPI(APIView):
     @super_admin_required
     def post(self, request):
         for k, v in request.data.items():
+            if k == "website_footer":
+                with XSSHtml() as parser:
+                    v = parser.clean(v)
             setattr(SysOptions, k, v)
         return self.success()
 
diff --git a/utils/models.py b/utils/models.py
index 3c11452..9a1cd0b 100644
--- a/utils/models.py
+++ b/utils/models.py
@@ -1,14 +1,10 @@
 from django.contrib.postgres.fields import JSONField  # NOQA
 from django.db import models
 
-from utils.xss_filter import XssHtml
+from utils.xss_filter import XSSHtml
 
 
 class RichTextField(models.TextField):
     def get_prep_value(self, value):
-        if not value:
-            value = ""
-        parser = XssHtml()
-        parser.feed(value)
-        parser.close()
-        return parser.getHtml()
+        with XSSHtml() as parser:
+            return parser.clean(value or "")
diff --git a/utils/xss_filter.py b/utils/xss_filter.py
index 34d65a8..1b45d89 100644
--- a/utils/xss_filter.py
+++ b/utils/xss_filter.py
@@ -30,7 +30,7 @@ import copy
 from html.parser import HTMLParser
 
 
-class XssHtml(HTMLParser):
+class XSSHtml(HTMLParser):
     allow_tags = ['a', 'img', 'br', 'strong', 'b', 'code', 'pre',
                   'p', 'div', 'em', 'span', 'h1', 'h2', 'h3', 'h4',
                   'h5', 'h6', 'blockquote', 'ul', 'ol', 'tr', 'th', 'td',
@@ -53,7 +53,17 @@ class XssHtml(HTMLParser):
         self.start = []
         self.data = []
 
-    def getHtml(self):
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        super().close()
+
+    def clean(self, content):
+        self.feed(content)
+        return self.get_html()
+
+    def get_html(self):
         """
         Get the safe html code
         """
@@ -188,11 +198,11 @@ class XssHtml(HTMLParser):
 
 
 if "__main__" == __name__:
-    parser = XssHtml()
-    parser.feed("""<p><img src=1 onerror=alert(/xss/)></p><div class="left">
-        <a href='javascript:prompt(1)'><br />hehe</a></div>
-        <p id="test" onmouseover="alert(1)">&gt;M<svg>
-        <a href="https://www.baidu.com" target="self">MM</a></p>
-        <embed src='javascript:alert(/hehe/)' allowscriptaccess=always />""")
-    parser.close()
-    print(parser.getHtml())
+    with XSSHtml() as parser:
+        ret = parser.clean("""<p><img src=1 onerror=alert(/xss/)></p><div class="left">
+            <a href='javascript:prompt(1)'><br />hehe</a></div>
+            <p id="test" onmouseover="alert(1)">&gt;M<svg>
+            <a href="https://www.baidu.com" target="self">MM</a></p>
+            <embed src='javascript:alert(/hehe/)' allowscriptaccess=always />
+            <img onerror=alert(1) src=#>""")
+        print(ret)