Highcharts Dashboards parses fullscreen labels as HTML

Impact

The edit mode fullscreen labels are parsed as HTML when the corresponding control is rendered. An attacker who controls the Dashboards language options can supply markup carrying event handlers, which then execute in the origin of the page hosting the dashboard. Exploitation requires that untrusted data reach the Dashboards language configuration and that the affected control be rendered. Script running this way has the same access to page data, storage and session state as the hosting application.

Workarounds

Until you can upgrade, replace Fullscreen.prototype.setButtonText atapplication startup. The replacement is the original method with textContent in place of innerHTML.

If you install Dashboards from npm

Import the module once, before any board is created.

import Fullscreen from '@highcharts/dashboards/es-modules/Dashboards/EditMode/Fullscreen.js';

Fullscreen.prototype.setButtonText = function () {
    const editMode = this.board.editMode,
        button = editMode?.tools.contextMenu?.items.viewFullscreen;

    if (button?.innerElement) {
        const lang = editMode.lang;

        button.innerElement.textContent =
            (this.isOpen ? lang.exitFullscreen : lang.viewFullscreen) || '';
    }
};

If you load Dashboards from a <script> tag

The same replacement, taking Fullscreen from the global namespace. It must run after modules/layout and before any board is created.

<script src="https://code.highcharts.com/dashboards/dashboards.js"></script>
<script src="https://code.highcharts.com/dashboards/modules/layout.js"></script>
<script>
{
    const Fullscreen = window.Dashboards?.Fullscreen;

    Fullscreen.prototype.setButtonText = function () {
        const editMode = this.board.editMode,
            button = editMode?.tools.contextMenu?.items.viewFullscreen;

        if (button?.innerElement) {
            const lang = editMode.lang;

            button.innerElement.textContent =
                (this.isOpen ? lang.exitFullscreen : lang.viewFullscreen) || '';
        }
    };
}
</script>

If your application does not need Edit Mode, leaving it disabled (editMode.enabled: false) removes the exposure as well. The same applies to the context menu — the label is only reachable when viewFullscreen is among editMode.contextMenu.items.

Obtaining the patched version

The patched releases are available from all the usual distribution channels. With npm, upgrade the affected package to the patched version listed above, for example npm install @highcharts/dashboards@4.2.3. If you load Highcharts Dashboards from a CDN, use a versioned URL, for example https://code.highcharts.com/dashboards/4.2.3/dashboards.js. For more on each installation method, see the installation guide.