How to fix npm vulnerabilities manually?

If you are absolutely certain you'd like to skip the audit, you can do so by appending --no-audit

 npm install --no-audit

lodash-cli in devDependencies doesn't affect how browser-sync works in your project, devDependencies are ignored when a package is installed as a dependency.

What audit report says is that it's easy-extender that has lodash dependency:

browser-sync > easy-extender > lodash        

It depends on Lodash 3, while the problem was fixed in Lodash 4. The problem could be fixed by forking easy-extender, updating it and installing it instead of the package from NPM public registry. But there is no real problem with this dependency.

audit report importance should be evaluated manually. Even if nested dependency has security risk, this doesn't mean that a feature that introduces this risk was used. This also doesn't mean that even if it's used, it introduces real risk due to how it's used.

browser-sync is development tool that isn't used in production, there are not so many scenarios where its vulnerabilities could be exploited. And Prototype Pollution isn't a vulnerability at all, just a notice that a package doesn't follow good practices, it can be ignored.

Generally, this is the way to fix reported vulnerabilities:

• Do a sanity check
• In case it's a real problem, check the repository of vulnerable package for existing issues and PRs
• In case there's none, submit an issue
• Fork a repository or use use existing PR as git dependency until it's fixed in NPM release
• In case of nested dependencies, do this at several levels of nesting

Most times it's expected that you won't advance beyond a sanity check, and the only problem is that a "vulnerability" clutters audit report and conceals real vulnerabilities.

patch-package can help to patch nested dependencies in-place but this won't affect the report.

It's possible to force specific dependency version in nested dependency in Yarn 1 and 2 with resolutions field, this will affect audit report. It may be possible to do this natively in NPM in future. Currently the alternative in NPM is third-party npm-force-resolutions utility that gives less control, currently it forces a resolution for all dependencies, not a specific one.

Notice that by forcing a dependency to use nested dependencies it wasn't designed to work with, it can become broken at any moment. This especially applies to npm-force-resolutions, which is a blunt tool and can affect many nested dependencies at once.