Unauthorized File Access
Versions of the npm CLI prior to 6.13.3 are vulnerable to an Arbitrary File Write. It is possible for packages to create symlinks to files outside of the
node_modules folder through the
bin field upon installation. A properly constructed entry in the package.json bin field would allow a package publisher to create a symlink pointing to arbitrary files on a user’s system when the package is installed.
This behavior is possible through install scripts. This vulnerability bypasses a user using the --ignore-scripts install option.
Thank you Daniel Ruf for responsibly reporting the issue!
Further information: npm blog post