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.