Feature: #94825 - New f:sanitize.html Fluid ViewHelper

See Issue #94825

Description

A new Fluid ViewHelper <f:sanitize.html> is available for use in any Fluid Template.

Unlike <f:format.html> the new ViewHelper does not fully rewrite the contents of the ViewHelper, but only cleans the HTML for incorrect / possibly bad code.

The htmlSanitize keeps all HTML code as is, but cleans up invalid and malicious code based on the third-party package typo3/html-sanitize.

An optional view-helper argument build allows using a defined preset, or a fully qualified class name of a builder instance as alternative, which has to implement \TYPO3\HtmlSanitizer\Builder\BuilderInterface. If not given, the configuration falls back to the best-practice sanitization preset for TYPO3’s base RTE configuration (called “default”).

Impact

The “default” preset of <f:sanitize.html> allows to explicitly sanitize user-submitted markup - for instance provided in rich-text input fields using the TYPO3 backend user interface. The default preset only supports common HTML tags and attributes that usually are expected to be safe - for instance <iframe>, <form>, <nav> or similar elements are not supported (currently) and not supposed to be defined by users or editors, but rather by the actual HTML Template which shouldn’t be fully wrapped in <f:sanitize.html>.

When to use the different ViewHelpers:

  • <f:format.html>

Use this for wrapping fields produced by RTE fields, which parses HTML and adds attributes, replaces TYPO3-internal links to pages or files, based on lib.parseFunc_RTE. For this reason, it is recommended to use this ViewHelper mainly in Frontend rendering.

This ViewHelper calls TYPO3’s “parseFunc”, which means that htmlSanitize is activated by default in TYPO3 installations.

Summarized: <f:format.html> does HTML sanitization plus rebuilding the HTML output based on the configuration from lib.parseFunc.

  • <f:sanitize.html>

This ViewHelper takes the HTML as is, and removes malicious HTML code. This is useful for HTML returned from external sources where the HTML-based content is untrusted. It can be used in Frontend and Backend environments.

  • <f:format.raw>

This ViewHelper just outputs the content as is, including all HTML. Use this ViewHelper only if the content can be fully trusted.

All of the ViewHelpers above do not escape any of the contents.