Highcharts: `javascript:` URL in credits.href runs script on click

Impact

A credits.href value beginning with javascript: is assigned to the window location when the credits label is clicked, without being checked against an allowed-scheme list. An attacker who controls the chart configuration can therefore run script in the origin of the page hosting the chart. Exploitation requires that untrusted data reach the chart configuration and that a user click the credits label. Charts built with Highcharts Stock, Maps and Gantt are included, since those ship from the same package as Core.

Workarounds

Drop-in fix - for any versions affected (5.0.0-13.0.2). Add the below IIFE to run after Highcharts is loaded, but before a chart is created.

!function(t){if(t&&t.Chart&&!t.Chart.prototype.creditsHrefPatched){var r=t.Chart.prototype,e=r.addCredits;r.addCredits=function(n){var o=t.merge(!0,this.options.credits,n);return o&&o.href&&!c(o.href)&&delete o.href,e.call(this,o)},r.creditsHrefPatched=!0}function c(r){var e=t.AST&&t.AST.allowedReferences||["https://","http://","mailto:","/","../","./","#"];return"string"==typeof r&&e.some(function(t){return 0===r.indexOf(t)})}}(Highcharts);

Live demo & testing

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@ 13.1.0. If you load Highcharts from the CDN, use the versioned URLs on code.highcharts.com, for example https://code.highcharts.com/13.1.0/highcharts.js. For more on each installation method, see the installation guide.