XSS vulnerability

Problem/Motivation

This module uses the value of the data-settings attribute without sanitizing dangerous options.

Steps to reproduce

1. Create a bundle with an image field that uses the Tiny Slider Carousel formatter.
2. As an attacker who can insert HTML in the page, insert this HTML:

  <div class="tiny-slider-wrapper" data-settings='{ "controlsText": ["&lt;img src=x onerror=alert()&gt;"] }'><span>XSS</span></div>
  

3. When the page is displayed, the JS is executed.

This is mitigated by the fact the default CKE config does not allow data attributes.
However Xss::filter() allows data attributes and this method is used by various contrib modules to sanitize user inputs.

For example this can be reproduced with the html_title module:
1. Enable the module
2. Create a node with this title:

<sub class="tiny-slider-wrapper" data-settings='{ "controlsText": ["&lt;img src=x onerror=alert()&gt;"] }'><sub>XSS</sub></sub>

Proposed resolution

I wonder if calling Drupal.checkPlain() on every setting would work of if it could break some legitimate settings.

Remaining tasks

User interface changes

API changes

Data model changes