{"id":"CVE-2026-118243","aliases":["EUVD-2026-112302","GHSA-jqgh-w3cc-7jqw"],"status":"published","title":"Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype`","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.","severity":{"version":"4.0","score":5.3,"vector":"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","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00351,"percentile":0.2906,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-1321"],"published":"2026-10-28T17:33:31Z","modified":"2026-11-03T10:30:16Z","fixes":[{"ecosystem":"npm","package":"@highcharts/dashboards","fixed_in":["4.2.2"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"npm","package":"@highcharts/dashboards","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0"},{"last_affected":"4.2.1"},{"fixed":"4.2.2"}]}]},{"source":"osv","ecosystem":"npm","package":"@highcharts/dashboards","ranges":[{"type":"SEMVER","events":[{"introduced":"1.0.0"},{"fixed":"4.2.2"}]}]}],"products":[{"vendor":"highcharts","product":"highcharts"}],"references":[{"url":"https://github.com/highcharts/highcharts/security/advisories/GHSA-jqgh-w3cc-7jqw","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/highcharts/highcharts/commit/ade5a41a700212f09133223ca990a3737d1d9ec6","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/highcharts/highcharts/releases/tag/dashboards-v4.2.2","tags":["x_refsource_MISC","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-118243","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-jqgh-w3cc-7jqw"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/118xxx/CVE-2026-118243.json","tags":["advisory"]},{"url":"https://github.com/highcharts/highcharts","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-118243","title":"Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype`","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.","status":"published","published":"2026-10-28T17:33:31.422Z","modified":"2026-11-02T20:26:32.947Z","cvss":[{"version":"4.0","score":5.3,"vector":"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","level":"medium","assessor":"cna"}],"cwes":["CWE-1321"],"updated_at":"2026-11-03T00:01:30.510858Z"}],"euvd":[{"id":"EUVD-2026-112302","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.","status":"published","published":"2026-10-28T17:33:31Z","modified":"2026-11-02T20:26:32Z","cvss":[{"version":"4.0","score":5.3,"vector":"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","level":"medium"}],"updated_at":"2026-11-03T05:08:37.390802Z"}],"ghsa":[{"id":"GHSA-jqgh-w3cc-7jqw","title":"Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype`","description":"### Impact\nThe 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.\n\nThe injected property is inert until other code on the page reads or enumerates it, so consequences depend on the consuming application.\n\n### Workarounds\n**Drop-in fix - for any Highcharts Dashboards versions affected (1.0.0-4.2.1).**\nAdd the below IIFE to run after Highcharts Dashboards is loaded. \n\n```\n!function(t){if(t\u0026\u0026t.DataCursor\u0026\u0026t.DataTable){var e=t.DataCursor.prototype,r=t.DataTable.prototype;e.tableIdPollutionPatched||(e.tableIdPollutionPatched=!0,null!==Object.getPrototypeOf((new t.DataCursor).listenerMap)\u0026\u0026['addListener','emitCursor','remitCursor','removeListener'].forEach(function(t){var r=e[t];r\u0026\u0026(e[t]=function(){var t;return t=this,['listenerMap','stateMap'].forEach(function(e){var r,a=t[e];a\u0026\u0026null!==Object.getPrototypeOf(a)\u0026\u0026(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\u0026\u0026'constructor'!==e||(e=t.uniqueKey(),this.autoId=!0),this.safeTableId=e}}))}}(Dashboards);\n```\n\n[Live demo \u0026 testing](https://jsfiddle.net/BlackLabel/jwqazb51/)\n\n### Obtaining the patched version\nThe 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).","status":"published","published":"2026-10-28T19:55:32Z","modified":"2026-10-28T19:55:35Z","cvss":[{"version":"4.0","score":5.3,"vector":"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","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T14:41:39.926569Z"}],"nvd":[{"id":"CVE-2026-118243","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.","status":"published","published":"2026-10-28T18:17:15.103Z","modified":"2026-11-02T21:17:26.02Z","cvss":[{"version":"4.0","score":5.3,"vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"medium","assessor":"secondary"}],"cwes":["CWE-1321"],"updated_at":"2026-11-04T18:06:24.696141Z"}],"osv":[{"id":"CVE-2026-118243","title":"Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype`","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.","status":"published","published":"2026-10-28T17:33:31.422Z","modified":"2026-11-04T02:30:29.609974074Z","cvss":[{"version":"4.0","score":5.3,"vector":"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","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-04T02:55:01.518827Z"},{"id":"GHSA-jqgh-w3cc-7jqw","title":"Highcharts Dashboards: `__proto__` data table id writes sync listeners to `Object.prototype`","description":"### Impact\nThe 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.\n\nThe injected property is inert until other code on the page reads or enumerates it, so consequences depend on the consuming application.\n\n### Workarounds\n**Drop-in fix - for any Highcharts Dashboards versions affected (1.0.0-4.2.1).**\nAdd the below IIFE to run after Highcharts Dashboards is loaded. \n\n```\n!function(t){if(t\u0026\u0026t.DataCursor\u0026\u0026t.DataTable){var e=t.DataCursor.prototype,r=t.DataTable.prototype;e.tableIdPollutionPatched||(e.tableIdPollutionPatched=!0,null!==Object.getPrototypeOf((new t.DataCursor).listenerMap)\u0026\u0026['addListener','emitCursor','remitCursor','removeListener'].forEach(function(t){var r=e[t];r\u0026\u0026(e[t]=function(){var t;return t=this,['listenerMap','stateMap'].forEach(function(e){var r,a=t[e];a\u0026\u0026null!==Object.getPrototypeOf(a)\u0026\u0026(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\u0026\u0026'constructor'!==e||(e=t.uniqueKey(),this.autoId=!0),this.safeTableId=e}}))}}(Dashboards);\n```\n\n[Live demo \u0026 testing](https://jsfiddle.net/BlackLabel/jwqazb51/)\n\n### Obtaining the patched version\nThe 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).","status":"published","published":"2026-10-28T19:55:32Z","modified":"2026-10-28T20:15:06.105499228Z","cvss":[{"version":"4.0","score":5.3,"vector":"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","level":"medium"}],"cwes":["CWE-1321"],"updated_at":"2026-11-02T15:46:50.687609Z"}]}}