Vega Expression Language scale expression function Cross Site Scripting

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.1 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2023-26486: 0.78% estimated exploitation activity in the next 30 days; percentile 55.81 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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); This can be viewed in the Vega online IDE at…

Published by the source

2 Mar 2023, 23:11 UTC

Last modified by the source

10 Sep 2026, 03:49 UTC

Source last checked

26 Oct 2026, 12:21 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-4vq7-882g-wcg4

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-4vq7-882g-wcg4

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# Patch Next advisory brief: CVE-2023-26486

Advisory: Vega Expression Language `scale` expression function Cross Site Scripting
IDs: CVE-2023-26486, GHSA-4vq7-882g-wcg4
Record: https://patchnext.com/advisories/cve-2023-26486 (revision 2, source checked 26 Oct 2026, 12:21 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: vega 5.23.0; vega-functions 5.13.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm vega: affected < 5.23.0; fixed in 5.23.0
- npm vega-functions: affected < 5.13.1; fixed in 5.13.1

## Suggested inspection (read-only)
- `npm ls vega --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls vega-functions --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on vega, vega-functions.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-4vq7-882g-wcg4 (OSV record GHSA-4vq7-882g-wcg4 lists affected ranges: npm vega-functions >=0 =0 <5.23.0 (fixed))
- Verified: https://github.com/advisories/GHSA-4vq7-882g-wcg4 (GitHub-reviewed advisory GHSA-4vq7-882g-wcg4 lists affected ranges: npm vega-functions >=0 =0 <5.23.0)

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