fix: add missing URI Security and Conig\App::$permittedURIChars

app/Config/App.php

@@ -59,6 +59,30 @@ class App extends BaseConfig
      */
     public string $uriProtocol = 'REQUEST_URI';
 
+    /*
+    |--------------------------------------------------------------------------
+    | Allowed URL Characters
+    |--------------------------------------------------------------------------
+    |
+    | This lets you specify which characters are permitted within your URLs.
+    | When someone tries to submit a URL with disallowed characters they will
+    | get a warning message.
+    |
+    | As a security measure you are STRONGLY encouraged to restrict URLs to
+    | as few characters as possible.
+    |
+    | By default, only these are allowed: `a-z 0-9~%.:_-`
+    |
+    | Set an empty string to allow all characters -- but only if you are insane.
+    |
+    | The configured value is actually a regular expression character group
+    | and it will be used as: '/\A[<permittedURIChars>]+\z/iu'
+    |
+    | DO NOT CHANGE THIS UNLESS YOU FULLY UNDERSTAND THE REPERCUSSIONS!!
+    |
+    */
+    public string $permittedURIChars = 'a-z 0-9~%.:_\-';
+
     /**
      * --------------------------------------------------------------------------
      * Default Locale

system/HTTP/Exceptions/BadRequestException.php

@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\HTTP\Exceptions;
+
+use CodeIgniter\Exceptions\HTTPExceptionInterface;
+use RuntimeException;
+
+/**
+ * 400 Bad Request
+ */
+class BadRequestException extends RuntimeException implements HTTPExceptionInterface
+{
+    /**
+     * HTTP status code for Bad Request
+     *
+     * @var int
+     */
+    protected $code = 400; // @phpstan-ignore-line
+}

system/Router/Router.php

@@ -13,6 +13,7 @@ namespace CodeIgniter\Router;
 
 use Closure;
 use CodeIgniter\Exceptions\PageNotFoundException;
+use CodeIgniter\HTTP\Exceptions\BadRequestException;
 use CodeIgniter\HTTP\Exceptions\RedirectException;
 use CodeIgniter\HTTP\Request;
 use CodeIgniter\HTTP\ResponseInterface;
@@ -120,11 +121,23 @@ class Router implements RouterInterface
 
     protected ?AutoRouterInterface $autoRouter = null;
 
+    /**
+     * Permitted URI chars
+     *
+     * The default value is `''` (do not check) for backward compatibility.
+     */
+    protected string $permittedURIChars = '';
+
     /**
      * Stores a reference to the RouteCollection object.
      */
     public function __construct(RouteCollectionInterface $routes, ?Request $request = null)
     {
+        $config = config(App::class);
+        if (isset($config->permittedURIChars)) {
+            $this->permittedURIChars = $config->permittedURIChars;
+        }
+
         $this->collection = $routes;
 
         // These are only for auto-routing
@@ -179,6 +192,8 @@ class Router implements RouterInterface
         // Decode URL-encoded string
         $uri = urldecode($uri);
 
+        $this->checkDisallowedChars($uri);
+
         // Restart filterInfo
         $this->filterInfo  = null;
         $this->filtersInfo = [];
@@ -676,4 +691,20 @@ class Router implements RouterInterface
 
         $this->matchedRouteOptions = $this->collection->getRoutesOptions($route);
     }
+
+    /**
+     * Checks disallowed characters
+     */
+    private function checkDisallowedChars(string $uri): void
+    {
+        foreach (explode('/', $uri) as $segment) {
+            if ($segment !== '' && $this->permittedURIChars !== ''
+                && preg_match('/\A[' . $this->permittedURIChars . ']+\z/iu', $segment) !== 1
+            ) {
+                throw new BadRequestException(
+                    'The URI you submitted has disallowed characters: "' . $segment . '"'
+                );
+            }
+        }
+    }
 }

tests/system/Router/RouterTest.php

@@ -13,10 +13,12 @@ namespace CodeIgniter\Router;
 
 use CodeIgniter\Config\Services;
 use CodeIgniter\Exceptions\PageNotFoundException;
+use CodeIgniter\HTTP\Exceptions\BadRequestException;
 use CodeIgniter\HTTP\Exceptions\RedirectException;
 use CodeIgniter\HTTP\IncomingRequest;
 use CodeIgniter\Router\Exceptions\RouterException;
 use CodeIgniter\Test\CIUnitTestCase;
+use Config\App;
 use Config\Modules;
 use Config\Routing;
 use Tests\Support\Filters\Customfilter;
@@ -87,6 +89,16 @@ final class RouterTest extends CIUnitTestCase
         $router->handle('0');
     }
 
+    public function testNotPermittedChars(): void
+    {
+        $router = new Router($this->collection, $this->request);
+
+        $this->expectException(BadRequestException::class);
+        $this->expectExceptionMessage('The URI you submitted has disallowed characters: "<a>"');
+
+        $router->handle('test/%3Ca%3E');
+    }
+
     public function testURIMapsToController(): void
     {
         $router = new Router($this->collection, $this->request);
@@ -783,6 +795,9 @@ final class RouterTest extends CIUnitTestCase
      */
     public function testRegularExpressionWithUnicode(): void
     {
+        $config                    = config(App::class);
+        $config->permittedURIChars = 'a-z 0-9~%.:_\-\x{0980}-\x{09ff}';
+
         $this->collection->get('news/([a-z0-9\x{0980}-\x{09ff}-]+)', 'News::view/$1');
 
         $router = new Router($this->collection, $this->request);
@@ -802,6 +817,9 @@ final class RouterTest extends CIUnitTestCase
      */
     public function testRegularExpressionPlaceholderWithUnicode(): void
     {
+        $config                    = config(App::class);
+        $config->permittedURIChars = 'a-z 0-9~%.:_\-\x{0980}-\x{09ff}';
+
         $this->collection->addPlaceholder('custom', '[a-z0-9\x{0980}-\x{09ff}-]+');
         $this->collection->get('news/(:custom)', 'News::view/$1');
 

user_guide_src/source/changelogs/v4.4.7.rst

@@ -10,6 +10,15 @@ Release Date: Unreleased
     :local:
     :depth: 3
 
+********
+SECURITY
+********
+
+- **URI Security:** The feature to check if URIs do not contain not permitted
+  strings has been added. This check is equivalent to the URI Security found in
+  CodeIgniter 3. This is enabled by default, but upgraded users need to add
+  a setting to enable it. See :ref:`urls-uri-security` for details.
+
 ********
 BREAKING
 ********

user_guide_src/source/concepts/security.rst

@@ -38,6 +38,7 @@ OWASP recommendations
 CodeIgniter provisions
 ======================
 
+- :ref:`urls-uri-security`
 - :ref:`invalidchars` filter
 - :doc:`../libraries/validation` library
 - :doc:`HTTP library <../incoming/incomingrequest>` provides for :ref:`input field filtering <incomingrequest-filtering-input-data>` & content metadata

user_guide_src/source/general/urls.rst

@@ -58,6 +58,39 @@ Route path /blog/news/2022/10                   The URI path relative to the Bas
 Query      page=2
 ========== ==================================== =========================================
 
+.. _urls-uri-security:
+
+URI Security
+============
+
+.. versionadded:: 4.4.7
+
+.. important::
+    Users upgrading from versions prior to v4.4.7 will need to add the following
+    to **app/Config/App.php** in order to use this feature::
+
+        public string $permittedURIChars = 'a-z 0-9~%.:_\-';
+
+CodeIgniter is fairly restrictive regarding which characters it allows in your
+URI strings (Route path) in order to help minimize the possibility that malicious
+data can be passed to your application. URIs may only contain the following:
+
+-  Alpha-numeric text (latin characters only)
+-  Tilde: ``~``
+-  Percent sign: ``%``
+-  Period: ``.``
+-  Colon: ``:``
+-  Underscore: ``_``
+-  Dash: ``-``
+-  Space: `` ``
+
+This setting can be changed by ``Config\App::$permittedURIChars``.
+
+.. note::
+    This check is performed by the ``Router``. The Router takes the URL-encoded
+    value held by the ``SiteURI`` class, decodes it, and then checks that it
+    does not contain not permitted strings.
+
 .. _urls-remove-index-php:
 
 Removing the index.php file

user_guide_src/source/installation/upgrade_447.rst

@@ -16,6 +16,18 @@ Please refer to the upgrade instructions corresponding to your installation meth
 Mandatory File Changes
 **********************
 
+URI Security
+============
+
+The feature to check if URIs do not contain not permitted strings has been added.
+This check is equivalent to the URI Security found in CodeIgniter 3.
+
+We recommend you enable this feature. Add the following to **app/Config/App.php**::
+
+        public string $permittedURIChars = 'a-z 0-9~%.:_\-';.
+
+See :ref:`urls-uri-security` for details.
+
 Error Files
 ===========
 
@@ -66,6 +78,9 @@ and it is recommended that you merge the updated versions with your application:
 Config
 ------
 
+- app/Config/App.php
+    - The property ``$permittedURIChars`` was added. See :ref:`urls-uri-security`
+      for details.
 - @TODO
 
 All Changes