Package Instance

Regex denial of service vulnerability in codesample plugin
### Impact
A regex denial of service (ReDoS) vulnerability was discovered in a dependency of the `codesample` plugin. The vulnerability allowed poorly formed ruby code samples to lock up the browser while performing syntax highlighting. This impacts users of the `codesample` plugin using TinyMCE 5.5.1 or lower.

### Patches
This vulnerability has been patched in TinyMCE 5.6.0 by upgrading to a version of the dependency without the vulnerability.

### Workarounds
To work around this vulnerability, either:
- Upgrade to TinyMCE 5.6.0 or higher
- Disable the `codesample` plugin
- Disable ruby code samples using the [codesample_languages](https://www.tiny.cloud/docs/plugins/opensource/codesample/#exampleusingcodesample_languages) setting
- Override the PrismJS syntax highlighter to version 1.21.0 or higher using the [codesample_global_prismjs](https://www.tiny.cloud/docs/plugins/opensource/codesample/#codesample_global_prismjs) setting

### Acknowledgements
Tiny Technologies would like to thank Erik Krogh Kristensen at GitHub for discovering this vulnerability.

### References
https://www.tiny.cloud/docs/release-notes/release-notes56/#securityfixes

### For more information
If you have any questions or comments about this advisory:
* Open an issue in the [TinyMCE repo](http://github.com/tinymce/tinymce/issues)
* Email us at [infosec@tiny.cloud](mailto:infosec@tiny.cloud)

Cross-site scripting vulnerability in TinyMCE
### Impact
A cross-site scripting (XSS) vulnerability was discovered in the URL sanitization logic of the core parser for `form` elements. The vulnerability allowed arbitrary JavaScript execution when inserting a specially crafted piece of content into the editor using the clipboard or APIs, and then submitting the form. However, as TinyMCE does not allow forms to be submitted while editing, the vulnerability could only be triggered when the content was previewed or rendered outside of the editor. This impacts all users who are using TinyMCE 5.7.0 or lower.

### Patches
This vulnerability has been patched in TinyMCE 5.7.1 by improved URL sanitization logic.

### Workarounds
To work around this vulnerability, either:
- Upgrade to TinyMCE 5.7.1 or higher
- Manually sanitize `form` URL attributes using a [TinyMCE node filter](https://www.tiny.cloud/docs/api/tinymce.html/tinymce.html.domparser/#addnodefilter).
- Disable `form` elements in your content using the [invalid_elements](https://www.tiny.cloud/docs/configure/content-filtering/#invalid_elements) setting.

#### Example: Sanitizing using a node filter
```js
editor.parser.addNodeFilter('form', function(nodes) {
  nodes.forEach(function(node) {
    if (node.attributes) {
      node.attributes.forEach(function(attr) {
        var name = attr.name;
        var value = attr.value;
        // Sanitize the attribute value here or remove it entirely
        var sanitizedValue = ...;
        node.attr(name, santizedValue);
      });
    }
  });
});
```

#### Example: Using invalid_elements
```js
invalid_elements: 'form'
```

### Acknowledgements
Tiny Technologies would like to thank Mikhail Khramenkov at Solar Security Research Team for discovering this vulnerability.

### References
https://www.tiny.cloud/docs/release-notes/release-notes571/#securityfixes

### For more information
If you have any questions or comments about this advisory:
* Open an issue in the [TinyMCE repo](https://github.com/tinymce/tinymce/issues)
* Email us at [infosec@tiny.cloud](mailto:infosec@tiny.cloud)