diff --git a/app/Observers/TopicObserver.php b/app/Observers/TopicObserver.php
index 6600dbefa..cb7c9f985 100644
--- a/app/Observers/TopicObserver.php
+++ b/app/Observers/TopicObserver.php
@@ -11,6 +11,8 @@ class TopicObserver
 {
     public function saving(Topic $topic)
     {
+        $topic->body = clean($topic->body, 'user_topic_body');
+
         $topic->excerpt = make_excerpt($topic->body);
     }
 }
diff --git a/composer.json b/composer.json
index ee8300ed0..8a6f86c35 100644
--- a/composer.json
+++ b/composer.json
@@ -14,6 +14,7 @@
         "laravel/framework": "^6.0",
         "laravel/tinker": "^1.0",
         "mews/captcha": "~3.0",
+        "mews/purifier": "~3.0",
         "overtrue/laravel-lang": "~3.0",
         "summerblue/laravel-active": "6.*"
     },
diff --git a/composer.lock b/composer.lock
index c5da0b49e..3100c48f8 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "4e16f3f17945ca8d299fdfd3132c3916",
+    "content-hash": "17df021621f3527a49cf3662ecaeac82",
     "packages": [
         {
             "name": "caouecs/laravel-lang",
@@ -411,6 +411,59 @@
             ],
             "time": "2019-03-17T18:48:37+00:00"
         },
+        {
+            "name": "ezyang/htmlpurifier",
+            "version": "v4.11.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/ezyang/htmlpurifier.git",
+                "reference": "83ab08bc1af7d808a9e0fbf024f1c24bfd73c0a7"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/ezyang/htmlpurifier/zipball/83ab08bc1af7d808a9e0fbf024f1c24bfd73c0a7",
+                "reference": "83ab08bc1af7d808a9e0fbf024f1c24bfd73c0a7",
+                "shasum": "",
+                "mirrors": [
+                    {
+                        "url": "https://mirrors.aliyun.com/composer/dists/%package%/%reference%.%type%",
+                        "preferred": true
+                    }
+                ]
+            },
+            "require": {
+                "php": ">=5.2"
+            },
+            "require-dev": {
+                "simpletest/simpletest": "dev-master#72de02a7b80c6bb8864ef9bf66d41d2f58f826bd"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-0": {
+                    "HTMLPurifier": "library/"
+                },
+                "files": [
+                    "library/HTMLPurifier.composer.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "LGPL-2.1-or-later"
+            ],
+            "authors": [
+                {
+                    "name": "Edward Z. Yang",
+                    "email": "admin@htmlpurifier.org",
+                    "homepage": "http://ezyang.com"
+                }
+            ],
+            "description": "Standards compliant HTML filter written in PHP",
+            "homepage": "http://htmlpurifier.org/",
+            "keywords": [
+                "html"
+            ],
+            "time": "2019-07-14T18:58:38+00:00"
+        },
         {
             "name": "fideloper/proxy",
             "version": "4.2.1",
@@ -1109,6 +1162,90 @@
             ],
             "time": "2019-09-05T22:33:04+00:00"
         },
+        {
+            "name": "mews/purifier",
+            "version": "3.1.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/mewebstudio/Purifier.git",
+                "reference": "bddf8a18fcbd123c81440768f68058c30a7e60e7"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/mewebstudio/Purifier/zipball/bddf8a18fcbd123c81440768f68058c30a7e60e7",
+                "reference": "bddf8a18fcbd123c81440768f68058c30a7e60e7",
+                "shasum": "",
+                "mirrors": [
+                    {
+                        "url": "https://mirrors.aliyun.com/composer/dists/%package%/%reference%.%type%",
+                        "preferred": true
+                    }
+                ]
+            },
+            "require": {
+                "ezyang/htmlpurifier": "4.11.*",
+                "illuminate/config": "5.1.* || 5.2.* || 5.3.* || 5.4.* || 5.5.* || 5.6.* || 5.7.* || 5.8.* || 6.0.*",
+                "illuminate/filesystem": "5.1.* || 5.2.* || 5.3.* || 5.4.* || 5.5.* || 5.6.* || 5.7.* || 5.8.* || 6.0.*",
+                "illuminate/support": "5.1.* || 5.2.* || 5.3.* || 5.4.* || 5.5.* || 5.6.* || 5.7.* || 5.8.* || 6.0.*",
+                "php": "^7.2"
+            },
+            "require-dev": {
+                "graham-campbell/testbench": "^3.2",
+                "mockery/mockery": "0.9.*",
+                "phpunit/phpunit": "^4.8|^5.0",
+                "scrutinizer/ocular": "^1.3"
+            },
+            "suggest": {
+                "laravel/framework": "To test the Laravel bindings",
+                "laravel/lumen-framework": "To test the Lumen bindings"
+            },
+            "type": "package",
+            "extra": {
+                "laravel": {
+                    "providers": [
+                        "Mews\\Purifier\\PurifierServiceProvider"
+                    ],
+                    "aliases": {
+                        "Purifier": "Mews\\Purifier\\Facades\\Purifier"
+                    }
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Mews\\Purifier\\": "src/"
+                },
+                "files": [
+                    "src/helpers.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Muharrem ERİN",
+                    "email": "me@mewebstudio.com",
+                    "homepage": "https://github.com/mewebstudio",
+                    "role": "Developer"
+                }
+            ],
+            "description": "Laravel 5/6 HtmlPurifier Package",
+            "homepage": "https://github.com/mewebstudio/purifier",
+            "keywords": [
+                "Purifier",
+                "htmlpurifier",
+                "laravel5 HtmlPurifier",
+                "laravel5 Purifier",
+                "laravel5 Security",
+                "laravel6 HtmlPurifier",
+                "laravel6 Purifier",
+                "laravel6 Security",
+                "security",
+                "xss"
+            ],
+            "time": "2019-09-09T10:53:00+00:00"
+        },
         {
             "name": "monolog/monolog",
             "version": "2.0.0",
diff --git a/config/purifier.php b/config/purifier.php
new file mode 100644
index 000000000..05d010cbf
--- /dev/null
+++ b/config/purifier.php
@@ -0,0 +1,17 @@
+<?php
+
+return [
+    'encoding'      => 'UTF-8',
+    'finalize'      => true,
+    'cachePath'     => storage_path('app/purifier'),
+    'cacheFileMode' => 0755,
+    'settings'      => [
+        'user_topic_body' => [
+            'HTML.Doctype'             => 'XHTML 1.0 Transitional',
+            'HTML.Allowed'             => 'div,b,strong,i,em,a[href|title],ul,ol,ol[start],li,p[style],br,span[style],img[width|height|alt|src],*[style|class],pre,hr,code,h2,h3,h4,h5,h6,blockquote,del,table,thead,tbody,tr,th,td',
+            'CSS.AllowedProperties'    => 'font,font-size,font-weight,font-style,margin,width,height,font-family,text-decoration,padding-left,color,background-color,text-align',
+            'AutoFormat.AutoParagraph' => true,
+            'AutoFormat.RemoveEmpty'   => true,
+        ],
+    ],
+];