CVE-2025-25304

The vlSelectionTuples function can be used to call JavaScript functions, leading to XSS.

Details

vlSelectionTuples calls multiple functions that can be controlled by an attacker, including one call with an attacker-controlled argument.

Example call: vlSelectionTuples([{datum:<argument>}], {fields:[{getter:<function>}]})

This can be used to call Function() with arbitrary JavaScript and the resulting function can be called with vlSelectionTuples or using a type coercion to call toString or valueOf.

PoC

{"$schema":"https://vega.github.io/schema/vega/v5.json","signals":[{"name":"a","init":"+{valueOf:vlSelectionTuples([{datum:'alert(1)'}],{fields:[{getter:[].at.constructor}]})[0].values[0]}"}]}

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

Kodem intelligence

1. What is CVE-2025-25304? CVE-2025-25304 is a medium-severity cross-site scripting (XSS) vulnerability in vega (npm), affecting versions < 5.26.0. It is fixed in 5.26.0, 5.4.2. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. Which packages are affected by CVE-2025-25304?
   • vega (npm) (versions < 5.26.0)
   • vega-selections (npm) (versions < 5.4.2)
3. Is there a fix for CVE-2025-25304? Yes. CVE-2025-25304 is fixed in 5.26.0, 5.4.2. Upgrade to this version or later.
4. Is CVE-2025-25304 exploitable, and should I be worried? Whether CVE-2025-25304 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2025-25304 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2025-25304?
   • Upgrade vega to 5.26.0 or later
   • Upgrade vega-selections to 5.4.2 or later