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Response snapshot Oct 29, 2026, 01:26 UTC

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VulnerabilityCVE-2026-118243

Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype`

The data cursor keeps its listener and state bookkeeping in plain objects keyed by data table id, so a table id of proto supplied in the dataPool connector configuration resolves to Object.prototype when a sync registers its listeners, and the registration creates a property on Object.

At a glance

Exploited
Not known
Severity
5.3 Medium (CVSS 4.0)
Chance of exploitation
Not estimated
Sources
1 source

What to do

GitHub lists first patched versions: @highcharts/dashboards: 4.2.2. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-jqgh-w3cc-7jqw (opens a new tab)

What happened

Impact

The data cursor keeps its listener and state bookkeeping in plain objects keyed by data table id, so a table id of proto supplied in the dataPool connector configuration resolves to Object.prototype when a sync registers its listeners, and the registration creates a property on Object.prototype named after the sync state and holding the internal listener array.

The property name begins with a state prefix fixed by the library, to which the sync group option can append an attacker-chosen suffix, and its value is the library's own listener array, but the property is enumerable and visible on every object in the page, and emitting a lasting state for that table id then throws, so syncs that keep lasting states, such as extremes, stop working.

Exploitation requires that untrusted data reach the Dashboards configuration and that a sync such as highlight or extremes be enabled on a component using that table, which the same configuration can do. No user interaction is required beyond loading the board.

Continue reading

The injected property is inert until other code on the page reads or enumerates it, so consequences depend on the consuming application.

Workarounds

Drop-in fix - for any Highcharts Dashboards versions affected (1.0.0-4.2.1). Add the below IIFE to run after Highcharts Dashboards is loaded.

!function(t){if(t&&t.DataCursor&&t.DataTable){var e=t.DataCursor.prototype,r=t.DataTable.prototype;e.tableIdPollutionPatched||(e.tableIdPollutionPatched=!0,null!==Object.getPrototypeOf((new t.DataCursor).listenerMap)&&['addListener','emitCursor','remitCursor','removeListener'].forEach(function(t){var r=e[t];r&&(e[t]=function(){var t;return t=this,['listenerMap','stateMap'].forEach(function(e){var r,a=t[e];a&&null!==Object.getPrototypeOf(a)&&(r=Object.create(null),Object.keys(a).forEach(function(t){r[t]=a[t]}),t[e]=r)}),r.apply(this,arguments)})}),'__proto__'!==new t.DataTable({id:'__proto__'}).id||Object.getOwnPropertyDescriptor(r,'id')||Object.defineProperty(r,'id',{configurable:!0,enumerable:!0,get:function(){return this.safeTableId},set:function(e){'__proto__'!==e&&'constructor'!==e||(e=t.uniqueKey(),this.autoId=!0),this.safeTableId=e}}))}}(Dashboards);

[Live demo & testing](https://jsfiddle.net/BlackLabel/jwqazb51/)

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@4.2.2. If you load Highcharts Dashboards from a CDN, use a versioned URL, for example https://code.highcharts.com/dashboards/4.2.2/dashboards.js. For more on each installation method, see the [installation guide](https://www.highcharts.com/docs/dashboards/installation).

Affected package ranges reported by GitHub: @highcharts/dashboards: >= 1.0.0, <= 4.2.1

Scores and how they were measured

CVSS base severity

5.3

Version 4.0As of

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:L/SI:L/SA:L

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-jqgh-w3cc-7jqw (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-jqgh-w3cc-7jqw, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 28). Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype` (CVE-2026-118243). https://kevwire.com/record/CVE-2026-118243

MLA

"Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype` (CVE-2026-118243)." KEVWire, 28 Oct. 2026, kevwire.com/record/CVE-2026-118243.

Chicago

KEVWire. "Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype` (CVE-2026-118243)." Last modified October 28, 2026. https://kevwire.com/record/CVE-2026-118243.

Evidence summary (plain text)

Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype` (Oct 28, 2026).
The data cursor keeps its listener and state bookkeeping in plain objects keyed by data table id, so a table id of proto supplied in the dataPool connector configuration resolves to Object.prototype when a sync registers its listeners, and the registration creates a property on Object.prototype named after the sync state and holding the internal listener array.
CVSS 5.3 (version 4.0; evidence as of Oct 28, 2026; https://github.com/advisories/GHSA-jqgh-w3cc-7jqw).
Sources:
GitHub-reviewed advisory GHSA-jqgh-w3cc-7jqw: https://github.com/advisories/GHSA-jqgh-w3cc-7jqw
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
Record ID: CVE-2026-118243.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 29, 2026, 00:55 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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