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CVE-2025-26619 — vega

Fix: vega/vega@8fc129a

CVE-2025-26619 is a Cross-site Scripting (XSS) vulnerability in vega. A fix is available for vega — see the affected versions and patch details below.

Vega Cross-Site Scripting (XSS) via event filter when not using CSP mode `expressionInterpeter`

Also known asGHSA-rcw3-wmx7-cphr
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Nov 6, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-26619.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs29th percentile — riskier than 29% of all scored CVEsHighest risk
0.00%0.31%0.61%0.92%0.2%0.4%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

302other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
veganpm
1.9Mdownloads / week
vega-functionsnpm
2.0Mdownloads / week

Description

Impact

In vega 5.30.0 and lower, vega-functions 5.15.0 and lower , it was possible to call JavaScript functions from the Vega expression language that were not meant to be supported.

Patches

Patched in vega 5.31.0 / vega-functions 5.16.0

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

  • Run vega without vega.expressionInterpreter. This mode is not the default as it is slower.
  • Using the interpreter described in CSP safe mode (Content Security Policy) prevents arbitrary Javascript from running, so users of this mode are not affected by this vulnerability.

References

Reproduction of the error in Vega by @mattijn

{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "signals": [
    {
      "name": "inject_alert",
      "on": [
        {
          "events": [
            {
              "type": "mousedown",
              "marktype": "rect",
              "filter": ["scale(event.view.setTimeout, 'alert(\"alert\")')"]
            }
          ],
          "update": "datum"
        }
      ]
    }
  ],
  "marks": [
    {
      "type": "rect",
      "encode": {
        "update": {
          "x": {"value": 0},
          "y": {"value": 0},
          "width": {"value": 100},
          "height": {"value": 100}
        }
      }
    }
  ]
}

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
📦npmvegaall versions5.31.0npm install vega@5.31.0
📦npmvega-functionsall versions5.16.0npm install vega-functions@5.16.0

Affected Products

2 products · 2 configurations
Application
vegavega_project
< 5.31.0
range
Application
vega-functionsvega-functions_project
< 5.16.0
range

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for vega, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update vega to 5.31.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-26619 is resolved across your whole dependency graph.

  3. Workarounds

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

### Impact In `vega` 5.30.0 and lower, `vega-functions` 5.15.0 and lower , it was possible to call JavaScript functions from the Vega expression language that were not meant to be supported. ### Patches Patched in `vega` `5.31.0` / `vega-functions` `5.16.0` ### Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_ - Run `vega` without `vega.expressionInterpreter`. This mode is not the default as it is slower. - Using the interpreter [described in CSP safe mode](https://vega.github.io/vega/usage/interpreter/) (Content Security Policy) prevents
O3 Security · Impact-Aware SCA

Is CVE-2025-26619 in your dependencies?

Find it across npm, including transitive dependencies.

CVE-2025-26619: vega — Fixed in 5.31.0