CVE-2022-46175

JSON5 is an extension to the popular JSON file format that aims to be
easier to write and maintain by hand (e.g. for config files). The parse
method of the JSON5 library before and including versions 1.0.1 and 2.2.1
does not restrict parsing of keys named __proto__, allowing specially
crafted strings to pollute the prototype of the resulting object. This
vulnerability pollutes the prototype of the object returned by
JSON5.parse and not the global Object prototype, which is the commonly
understood definition of Prototype Pollution. However, polluting the
prototype of a single object can have significant security impact for an
application if the object is later used in trusted operations. This
vulnerability could allow an attacker to set arbitrary and unexpected keys
on the object returned from JSON5.parse. The actual impact will depend on
how applications utilize the returned object and how they filter unwanted
keys, but could include denial of service, cross-site scripting, elevation
of privilege, and in extreme cases, remote code execution. JSON5.parse
should restrict parsing of __proto__ keys when parsing JSON strings to
objects. As a point of reference, the JSON.parse method included in
JavaScript ignores __proto__ keys. Simply changing JSON5.parse to
JSON.parse in the examples above mitigates this vulnerability. This
vulnerability is patched in json5 versions 1.0.2, 2.2.2, and later.