Description
tinymce is an open source rich text editor. A cross-site scripting (XSS) vulnerability was discovered in the alert and confirm dialogs when these dialogs were provided with malicious HTML content. This can occur in plugins that use the alert or confirm dialogs, such as in the `image` plugin, which presents these dialogs when certain errors occur. The vulnerability allowed arbitrary JavaScript execution when an alert presented in the TinyMCE UI for the current user. This vulnerability has been patched in TinyMCE 5.10.7 and TinyMCE 6.3.1 by ensuring HTML sanitization was still performed after unwrapping invalid elements. Users are advised to upgrade to either 5.10.7 or 6.3.1. Users unable to upgrade may ensure the the `images_upload_handler` returns a valid value as per the images_upload_handler documentation.
Remediation
References
https://github.com/tinymce/tinymce/commit/6923d85eba6de3e08ebc9c5a387b5abdaa21150e
https://www.tiny.cloud/docs/tinymce/6/file-image-upload/#images_upload_handler
https://www.tiny.cloud/docs/release-notes/release-notes5107/#securityfixes
https://github.com/tinymce/tinymce/commit/8bb2d2646d4e1a718fce61a775fa22e9d317b32d
https://github.com/tinymce/tinymce/security/advisories/GHSA-gg8r-xjwq-4w92
https://www.tiny.cloud/docs/tinymce/6/6.3-release-notes/#security-fixes