Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. Prior to version 5.26.0 of vega and 5.4.2 of vega-selections, the `vlSelectionTuples` function can be used to call JavaScript functions, leading to cross-site scripting.`vlSelectionTuples` calls multiple functions that can be controlled by an attacker, including one call with an attacker-controlled argument. 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`. Version 5.26.0 of vega and 5.4.2 of vega-selections fix this issue.

Affected: npm: vega, npm: vega-selections

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

### Details [`vlSelectionTuples`](https://github.com/vega/vega/blob/b45cf431cd6c0d0c0e1567f087f9b3b55bc236fa/packages/vega-selections/src/selectionTuples.js#L14) 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]}"}]} ```

Affected: Ubuntu:24.04:LTS: vega.js, Ubuntu:25.10: vega.js, Ubuntu:26.04:LTS: vega.js

Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. Prior to version 5.26.0 of vega and 5.4.2 of vega-selections, the `vlSelectionTuples` function can be used to call JavaScript functions, leading to cross-site scripting.`vlSelectionTuples` calls multiple functions that can be controlled by an attacker, including one call with an attacker-controlled argument. 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`. Version 5.26.0 of vega and 5.4.2 of vega-selections fix this issue.