Description
An issue was discovered in an npm 5.7.0 2018-02-21 pre-release (marked as "next: 5.7.0" and therefore automatically installed by an "npm upgrade -g npm" command, and also announced in the vendor's blog without mention of pre-release status). It might allow local users to bypass intended filesystem access restrictions because ownerships of /etc and /usr directories are being changed unexpectedly, related to a "correctMkdir" issue.
Remediation
References
https://github.com/npm/npm/issues/19883
https://github.com/npm/npm/commit/74e149da6efe6ed89477faa81fef08eee7999ad0
http://blog.npmjs.org/post/171169301000/v571