Affected versions of `yargs-parser` are vulnerable to prototype pollution. Arguments are not properly sanitized, allowing an attacker to modify the prototype of `Object`, causing the addition or modification of an existing property that will exist on all objects. Parsing the argument `--foo.__proto__.bar baz'` adds a `bar` property with value `baz` to all objects. This is only exploitable if attackers have control over the arguments being passed to `yargs-parser`. ## Recommendation Upgrade to versions 13.1.2, 15.0.1, 18.1.1 or later.