A cross-site scripting (XSS) vulnerability was discovered in: the core parser and media plugin. The vulnerability allowed arbitrary JavaScript execution when inserting a specially crafted piece of content into the editor via the clipboard or APIs. This impacts all users who are using TinyMCE 4.9.9 or lower and TinyMCE 5.2.1 or lower.
Patches
This vulnerability has been patched in TinyMCE 4.9.10 and 5.2.2 by improved HTML parsing and sanitization logic.
Workarounds
The workarounds available are:
disable the media plugin and manually sanitize CDATA content (see below)
or
upgrade to either TinyMCE 4.9.10 or TinyMCE 5.2.2
Example: Manually strip CDATA elements
setup: function(editor) {
editor.on('PreInit', function() {
editor.parser.addNodeFilter('#cdata', function(nodes) {
for (var i = 0; i < nodes.length; i++) {
nodes[i].remove();
}
});
});
}
Acknowledgements
Tiny Technologies would like to thank Michał Bentkowski and intivesec for discovering these vulnerabilities.