TinyMCE 5.10.9


TinyMCE 5.10.9 was released for TinyMCE Enterprise and Tiny Cloud on Wednesday, November 15th, 2023. It includes TinyMCE 5.10.9. These release notes provide an overview of the changes for TinyMCE 5.10.9, including:

This is the Tiny Cloud and TinyMCE Enterprise release notes. For information on the latest community version of TinyMCE, see: TinyMCE Changelog.

Security fixes

TinyMCE 5.10.9 provides a fix for the following security issue:

Special characters in unescaped text nodes can trigger mXSS when using TinyMCE undo/redo, getContentAPI, resetContentAPI, and Autosave plugin

A mutation cross-site scripting (mXSS) vulnerability was discovered in TinyMCE’s core undo/redo functionality and other APIs and plugins. Text nodes within specific parents are not escaped upon serialization according to the HTML standard. If such text nodes contain a special character reserved as an internal marker, they can be combined with other HTML patterns to form malicious snippets. These snippets pass the initial sanitization layer when the content is parsed into the editor body, but can trigger XSS when the special internal marker is removed from the content and re-parsed. Such mutations occur when serialized HTML content is processed before being stored in the undo stack, or when the following APIs and plugins are used:

This vulnerability also impacts these related TinyMCE APIs and plugins:

This vulnerability has been patched in TinyMCE 5.10.9 by:

  • ensuring that any unescaped text nodes which contain the special internal marker are emptied before removing the marker from the rest of the HTML, and;

  • removing the special internal marker from content strings passed to Editor.setContent, Editor.insertContent, and Editor.resetContent APIs to prevent them from being loaded into the editor as user-provided content.

GHSA: GitHub Advisories. NOTE: Tiny Technologies would like to thank Masato Kinugawa of Cure53 for discovering this vulnerability.

Upgrading to the latest version of TinyMCE 5

The procedure for upgrading to the latest version of TinyMCE 5 depends on the deployment type.

Upgrading Tiny Cloud

Tiny Cloud provides the latest enterprise version of TinyMCE. For information on configuring Tiny Cloud, see: the Cloud deployment guide.

Upgrading TinyMCE Self-hosted manually

To upgrade to TinyMCE 5.10 using a manually downloaded package:

  1. Backup the tinymce/ directory so any customizations can be restored after the upgrade.

    Customizations for TinyMCE are typically stored in the following directories:

    ├── icons/
    ├── langs/
    ├── plugins/
    ├── skins/
    │   ├── content/
    │   └── ui/
    └── themes/
  2. Download the latest version of TinyMCE.

    • For the TinyMCE Community Version, download tinymce_<VERSION>.zip from Get TinyMCE - Self-hosted releases, where <VERSION> is the latest version of TinyMCE.

    • For the TinyMCE Enterprise Version, download the TinyMCE Enterprise Bundle from Tiny Account > Downloads. The downloaded file will be named enterprise_latest.zip.

  3. Extract the downloaded .zip file to a temporary location.

  4. (If required) Install the latest language packs from Get TinyMCE - Language Packages.

  5. Copy customizations to the new tinymce/ directory. Ensure that only custom changes are added the new tinymce/ directory, such as:

    • Custom icons packs

    • Custom plugins

    • Custom skins

    • Custom themes

  6. Delete the existing tinymce/ directory and replace with the new tinymce/.

To simplify the upgrade process to future versions of TinyMCE:

  1. Host the TinyMCE customizations outside of the tinymce/ directory.

  2. Update your TinyMCE configuration as required:

    • Set the location of content CSS customizations using content_css.

    • Set the location of custom plugins using external_plugins.

    • Set the location of custom icon packages using icons_url instead of icons.

    • Set the location of custom localization packages using language_url instead of language.

    • Set the location of custom skin packages using skin_url instead of skin.

    • Set the location of custom themes using theme_url instead of theme.