JupyterLab: Cross-site scripting (XSS) in JupyterLab via crafted language package (jupyterlab.json)

DescriptionA language pack ships a Plural-Forms header saying how the language counts, for example nplurals=2; plural=n != 1;. JupyterLab turns that string into a function with new Function, so the header gets executed. The check that meant to keep it safe was a regular expression. The regex was...