GHSA-gg8r-xjwq-4w92 Cross-site scripting vulnerability in TinyMCE alerts

• npm tinymce: >= 6.0.0, < 6.3.1 → fixed in 6.3.1 • Packagist tinymce/tinymce: >= 6.0.0, < 6.3.1 → fixed in 6.3.1 • NuGet TinyMCE: >= 6.0.0, < 6.3.1 → fixed in 6.3.1 • npm tinymce: < 5.10.7 → fixed in 5.10.7 • Packagist tinymce/tinymce: < 5.10.7 → fixed in 5.10.7 • NuGet TinyMCE: < 5.10.7 → fixed in 5.10.7

Impact 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. Patches 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. Fix To avoid this vulnerability: • Upgrade to TinyMCE 5.10.7 or higher for TinyMCE 5.x. • Upgrade to TinyMCE 6.3.1 or higher for TinyMCE 6.x. Workaround To reduce the impact of this vulnerability: • Ensure the the `images_upload_handler` returns a valid value as per the images_upload_handler documentation. References • https://www.tiny.cloud/docs/release-notes/release-notes5107/#securityfixes • https://www.tiny.cloud/docs/tinymce/6/6.3-release-notes/#security-fixes For more information If you have any questions or comments about this advisory: • Email us at [email protected] • Open an issue in the TinyMCE repo