GHSA-w7jx-j77m-wp65 Cross-site scripting vulnerability in TinyMCE

• npm tinymce: < 5.6.0 → fixed in 5.6.0 • NuGet TinyMCE: < 5.6.0 → fixed in 5.6.0 • Packagist tinymce/tinymce: < 5.6.0 → fixed in 5.6.0

Impact A cross-site scripting (XSS) vulnerability was discovered in the URL sanitization logic of the core parser. The vulnerability allowed arbitrary JavaScript execution when inserting a specially crafted piece of content into the editor using the clipboard or APIs. This impacts all users who are using TinyMCE 5.5.1 or lower. Patches This vulnerability has been patched in TinyMCE 5.6.0 by improved URL sanitization logic. Workarounds To work around this vulnerability, either: • Upgrade to TinyMCE 5.6.0 or higher • Manually sanitize `iframe`, `object` and `embed` URL attributes using a TinyMCE node filter. • Disable `iframe`, `object`, and `embed` elements in your content using the invalid_elements setting. Example: Sanitizing using a node filter ```js editor.parser.addNodeFilter('iframe,object,embed', 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: 'iframe,object,embed' ``` Acknowledgements Tiny Technologies would like to thank Aaron Bishop at SecurityMetrics 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 • Email us at [email protected]