Vega is a visualization grammar, a declarative format for creating, saving, and sharing interactive visualization designs. In `vega` 5.30.0 and lower and in `vega-functions` 5.15.0 and lower , it was possible to call JavaScript functions from the Vega expression language that were not meant to be supported. The issue is patched in `vega` `5.31.0`  and `vega-functions` `5.16.0`. Some workarounds are available. Run `vega` without `vega.expressionInterpreter`. This mode is not the default as it is slower. Alternatively, using the interpreter described in CSP safe mode (Content Security Policy) prevents arbitrary Javascript from running, so users of this mode are not affected by this vulnerability.