# 4.4.7

## Security patches

This release contains security patches. Some of those patches might require some updates to your project.

* [CVE-2020-9309 Script execution on protected files](https://www.silverstripe.org/download/security-releases/CVE-2020-9309)
* [CVE-2019-19326 Web Cache Poisoning](https://www.silverstripe.org/download/security-releases/CVE-2019-19326)
* [CVE-2020-6164 Information disclosure on /interactive URL path](https://www.silverstripe.org/download/security-releases/CVE-2020-6164)


### CVE-2020-9309 Script execution on protected files {#CVE-2020-9309}

Silverstripe can be susceptible to script execution from malicious upload contents under allowed file extensions (for example HTML code in a TXT file). When these files are stored as protected or draft files, the MIME detection can cause browsers to execute the file contents.

#### Risk factors

If your project already includes the `silverstripe/mimevalidator` module, it's already protected. CWP projects are already protected.

If your project includes the `silverstripe/userforms` module or allows anonymous users to upload files, it's at a higher risk because malicious users can create files without requiring a CMS access.

#### Actions you need to take

If your project already includes the `silverstripe/mimevalidator` module, you do not need to do anything. To check if the `silverstripe/mimevalidator` module is installed in your project, run this command from your project root.

```sh
composer show silverstripe/mimevalidator
```

If you get an error, the module is not installed.

**Upgrading to `silverstripe/recipe-cms` 4.4.7 will NOT automatically install `silverstripe/mimevalidator`**. You need to manually install the module `silverstripe/mimevalidator`. To add `silverstripe/mimevalidator` to your project, run this command.

```sh
composer require silverstripe/mimevalidator
```

After installing the `mimevalidator` module, you need to enable it by adding this code snippet to your YML configuration.

```yml
SilverStripe\Core\Injector\Injector:
  SilverStripe\Assets\Upload_Validator:
    class: SilverStripe\MimeValidator\MimeUploadValidator
```

If your project overrides the defaults allowed file types, it's important that you take the time to review your configuration and adjust it as need be to work with `silverstripe/mimevalidator`.

Read the [Allowed file types](/Developer_Guides/Files/Allowed_file_types) documentation for more details on controlling the type of files that can be stored in your Silverstrip CMS Project.

#### Special consideration when upgrading Userforms

The `silverstripe/userforms` module now also includes `silverstripe/mimevalidator` in its dependencies. Upgrading to the following versions of userforms will automatically install `silverstripe/mimevalidator`:

* 5.4.3 or later
* 5.5.3 or later
* 5.6.0 or later (requires CMS 4.6.0)

Userforms that include a file upload field will automatically use the`MimeUploadValidator`. Beware that this will NOT change the default upload validator for other file upload fields in the CMS. You'll need to update your YML configuration for the `MimeUploadValidator` to be used everywhere.

### CVE-2019-19326 Web Cache Poisoning {#CVE-2019-19326}

Silverstripe sites using HTTP cache headers and HTTP caching proxies (e.g. CDNs) can be susceptible to web cache poisoning through the:
* `X-Original-Url` HTTP header
* `X-HTTP-Method-Override` HTTP header
* `_method` POST variable.

In order to remedy this vulnerability, Silverstripe Framework 4.4.7 removes native support for these features. While this is technically a semantic versioning breakage, these features are inherently insecure and date back to a time when browsers didn't natively support the full range of HTTP methods. Sites who still require these features will have highly unusual requirements that are best served by a tailored solution.

### Re-enabling the support for removed features

These features are best implemented by defining a `Middleware`.

The following example illustrates how to implement an `HTTPMiddleware` that restores support for the `X-Original-Url` header and the `_method` POST parameter for requests originating from a trusted proxy.

```php
<?php
use SilverStripe\Control\Middleware\HTTPMiddleware;
use SilverStripe\Control\HTTPRequest;
/**
 * This is meant to illustrate how to implement an HTTPMiddleware. If you blindly
 * copy-paste this in in your code base, you'll simply replicate the vulnerability.
 */
class InsecureHeaderMiddleware implements HTTPMiddleware
{
    public function process(HTTPRequest $request, callable $delegate)
    {
        // Normally, you would validate that the request is coming from a trusted source at this point.
        // View SilverStripe\Control\Middleware\TrustedProxyMiddleware for an example.
        $trustedProxy = true;
        if ($trustedProxy) {
            $originalUrl = $request->getHeader('X-Original-Url');
            if ($originalUrl) {
                $_SERVER['REQUEST_URI'] = $originalUrl;
                $request->setUrl($originalUrl);
            }
            $methodOverride = $request->postVar('_method');
            $validMethods = ['GET', 'POST', 'PUT', 'DELETE', 'HEAD'];
            if ($methodOverride && in_array(strtoupper($methodOverride), $validMethods)) {
                $request->setHttpMethod($methodOverride);
            }
        }
        return $delegate($request);
    }
}
```

To learn more about re-implementing support for the disabled features:
* read [how to configure trusted proxies](/developer_guides/security/secure_coding/#request-hostname-forgery) on the Silverstripe documentation.
* read the [documentation about HTTP Middlewares](/developer_guides/controllers/middlewares/).

### CVE-2020-6164 Information disclosure on /interactive URL path

A specific URL path configured by default through the silverstripe/framework module can be used to disclose the fact that a domain is hosting a Silverstripe application. There is no disclosure of the specific version. The functionality on this URL path is limited to execution in a CLI context, and is not known to present a vulnerability through web-based access. As a side-effect, this preconfigured path also blocks the creation of other resources on this path (e.g. a page).

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## Change Log

### Security

 * 2020-05-13 [91d30db88](https://github.com/silverstripe/silverstripe-framework/commit/91d30db88f68b9b87980ef9a59e208a81980b72c) Remove/deprecate unused controllers that can potentially give away some information about the underlying project. (Maxime Rainville) - See [cve-2020-6164](https://www.silverstripe.org/download/security-releases/cve-2020-6164)
 * 2020-05-11 [107706c12](https://github.com/silverstripe/silverstripe-framework/commit/107706c12cd9cf4d1b8b96b6a6e223633209d851) Stop honouring X-HTTP-Method-Override header, X-Original-Url header and _method POST variable. Add SS_HTTPRequest::setHttpMethod() (Maxime Rainville) - See [cve-2019-19326](https://www.silverstripe.org/download/security-releases/cve-2019-19326)

### Bugfixes

 * 2020-06-01 [3df2222](https://github.com/silverstripe/silverstripe-asset-admin/commit/3df222203ee563fac840e5e0727c75ddfe244886) Prevent react-selectable from interfering with pagination (Maxime Rainville)
 * 2020-05-05 [2cc037b](https://github.com/silverstripe/silverstripe-versioned/commit/2cc037b2d305ed98056a9232587351949e59561f) Fix merge conflict in Travis configuration (Robbie Averill)
 * 2020-02-24 [bba0f2f72](https://github.com/silverstripe/silverstripe-framework/commit/bba0f2f72fa2e631dbf60357a908d5d57d4467ee) Fixed issue where TimeField_Readonly would only show "(not set)" instead of the value (UndefinedOffset)
 * 2020-02-18 [e0de15f](https://github.com/silverstripe/silverstripe-errorpage/commit/e0de15f85a09ac848cb110f49cef58624d1e892f) Fix broken test when FulltextSearchable is enabled (Maxime Rainville)
 * 2019-09-02 [6d8a4bc](https://github.com/silverstripe/silverstripe-assets/commit/6d8a4bc4f4178c0b56ede1b01f87b162066d550a) Make AbsoluteLink work with manipulated images (fixes #322) (Loz Calver)
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