Summary
Highcharts: series column construction writes to Object.prototype
Workarounds
Drop-in fix - for any versions affected (6.1.0-13.0.2).
Add the below IIFE to run after Highcharts is loaded.
;!function(t){if(t&&t.Point&&!t.Point.prototype.protoPollutionPatched){var o=t.Point.prototype,r=o.optionsToObject,e=o.setNestedProperty,n=Object.prototype.hasOwnProperty;o.optionsToObject=function(t){if(t&&"object"==typeof t&&!Array.isArray(t)&&(n.call(t,"__proto__")||n.call(t,"constructor"))){var o={};for(var e in t)n.call(t,e)&&!c(e)&&(o[e]=t[e]);t=o}return r.call(this,t)},o.setNestedProperty=function(t,o,r){return String(r).split(".").some(c)?t:e.call(this,t,o,r)},o.protoPollutionPatched=!0}function c(t){return"__proto__"===t||"constructor"===t}}(Highcharts);
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 [email protected]. 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.
Impact
When series columns are built from point objects, the point option keys are used directly as data column ids, so the write that populates a column reaches Object.prototype and the Object constructor. Keys named __proto__ and constructor survive JSON.parse as own enumerable properties, so an attacker who controls the point objects can set integer-keyed properties on Object.prototype, one per point index, to values of their choosing. Named properties cannot be reached this way. The integer keys still affect every object in the page: reading an out-of-range index on any array or plain object returns the attacker's value, and for...in over any object yields the injected keys, so unrelated code can take branches it should not using attacker-supplied data, and rendering can fail as a side effect. The properties remain in place once the chart has been built, and no user interaction is required beyond rendering the chart.
Consequences beyond disruption depend on the consuming application.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-118249? CVE-2026-118249 is a high-severity security vulnerability in highcharts (npm), affecting versions >= 13.0.0, <= 13.0.2. It is fixed in 13.1.0.
- Which versions of highcharts are affected by CVE-2026-118249? highcharts (npm) versions >= 13.0.0, <= 13.0.2 is affected.
- Is there a fix for CVE-2026-118249? Yes. CVE-2026-118249 is fixed in 13.1.0. Upgrade to this version or later.
- Is CVE-2026-118249 exploitable, and should I be worried? Whether CVE-2026-118249 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-118249 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-118249? Upgrade
highchartsto 13.1.0 or later.