CVE-2026-118243 Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype`
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-118243?
CVE-2026-118243 is a medium-severity vulnerability in highcharts, published on 28 Oct 2026.
Official description
Highcharts JS is a JavaScript charting library based on SVG. From 1.0.0 until 4.2.2, Highcharts Dashboards stores DataCursor listener and state maps in plain objects keyed by DataTable ID. A __proto__ table ID supplied through dataPool connector configuration resolves to Object.prototype, and sync registration creates an enumerable property there whose suffix can be influenced through the sync group option. The property is visible on every object, and lasting sync states can throw and stop features such as extremes synchronization. Exploitation requires untrusted dashboard configuration and an enabled component sync, but no user interaction beyond loading the board. This issue is fixed in 4.2.2.
Weakness: CWE-1321
Which versions are affected by CVE-2026-118243?
2 open source packages ship an affected version, including @highcharts/dashboards.
| Package | Affected | Fixed in |
|---|---|---|
@highcharts/dashboards npm | From 1.0.0 | 4.2.2 |
@highcharts/dashboards npm | From 1.0.0 | 4.2.2 |
How do I fix CVE-2026-118243?
Upgrade @highcharts/dashboards to 4.2.2 or later.
Is CVE-2026-118243 being exploited?
There is no known exploitation of CVE-2026-118243 in the wild and no public exploit code.
Sources
Also known as GHSA-jqgh-w3cc-7jqw.