# CVE-2026-118247: Highcharts Dashboards / Grid Pro: `DataTable.setCell` and column writers treat `__proto__` as an existing column.

Status: published. Published: 2026-10-28. Updated: 2026-11-02.

Highcharts JS is a JavaScript charting library based on SVG. From 1.0.0 until Dashboards 4.2.2, and from 2.0.0 until Grid Pro 3.2.0, Highcharts DataTable single-cell writers use an untrusted column ID as a key without rejecting __proto__ or constructor. DataTable.setCell, including Dashboards connector write-back and Grid Pro editing paths, can therefore write integer-indexed values onto Object.prototype or the Object constructor. In Dashboards releases with column aliases, a literal __proto__ ID is redirected by the alias map, while an alias targeting __proto__ reaches the unsafe write; later releases without aliases accept the unsafe ID directly. Those inherited values affect array and object reads and for-in enumeration throughout the page, which can alter application control flow or disrupt rendering. Exploitation requires control of the table or component column ID and a cell, point, or API write. This issue is fixed in Dashboards 4.2.2 and Grid Pro 3.2.0.

## Remediation

- fix: @highcharts/dashboards (npm): OSV reports a fixed version 4.2.2. Check the advisory for supported release branches. (source: OSV GHSA-c75x-9x9h-28rm) — https://github.com/advisories/GHSA-c75x-9x9h-28rm
- fix: @highcharts/grid-pro (npm): OSV reports a fixed version 3.2.0. Check the advisory for supported release branches. (source: OSV GHSA-c75x-9x9h-28rm) — https://github.com/advisories/GHSA-c75x-9x9h-28rm

## Affected products and versions

- highcharts / highcharts: < 13.1.0 (affected). Source: CNA: GitHub_M
- @highcharts / dashboards: >= 1.0.0, < 4.2.3 (affected). Source: CNA: GitHub_M
- @highcharts / grid-pro: >= 2.0.0, < 3.2.0 (affected). Source: CNA: GitHub_M
-  / @highcharts/dashboards (@highcharts/dashboards): ≥ 1.0.0; < 4.2.2 (affected, semver); OSV events: introduced 1.0.0; fixed 4.2.2. Source: OSV GHSA-c75x-9x9h-28rm
-  / @highcharts/grid-pro (@highcharts/grid-pro): ≥ 2.0.0; < 3.2.0 (affected, semver); OSV events: introduced 2.0.0; fixed 3.2.0. Source: OSV GHSA-c75x-9x9h-28rm

## Severity and prioritization

- CVSS 4.0: 6.9 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:N/VI:L/VA:H/SC:L/SI:L/SA:L; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: 0.36% as of 2026-11-02; percentile 30.15%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-1321

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/highcharts/highcharts/security/advisories/GHSA-c75x-9x9h-28rm (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/highcharts/highcharts/commit/02dd9349aeb6f4cc9c98806120d917ed316b4c74 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/highcharts/highcharts/releases/tag/dashboards-v4.2.2 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/highcharts/highcharts/releases/tag/grid-v3.2.0 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/advisories/GHSA-c75x-9x9h-28rm (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-c75x-9x9h-28rm (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-118247; retrieved 2026-11-02; source updated 2026-11-02

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-c75x-9x9h-28rm; retrieved 2026-11-02; source updated 2026-10-28

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-118247; retrieved 2026-11-02; source updated Not reported

Revision: 30bcf217fd7904d9843fb7d5f021a55a2d27b337e6981522f799faeb8205a5fb

Canonical: https://y2.dev/cve/CVE-2026-118247

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- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

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