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Multiple slashes can bypass null exports path #44316

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@privatenumber

Description

@privatenumber

Version

v16.17.0

Platform

macOS 12.4

Subsystem

No response

Description

Setting null on an export path can be used to exclude private directories from being exposed (Node.js docs):

// ./node_modules/package/package.json
{
    "exports": {
        "./*": "./*",
        "./internal/*": null
    }
}

Although this works to prevent an import like this:

import 'package/internal/file.js'

It can be circumvented by using multiple slashes:

import 'package//internal/file.js'

In UNIX, multiple consecutive slashes are treated as a single slash.

What steps will reproduce the bug?

StackBlitz reproduction

https://stackblitz.com/edit/node-auughm?file=index.js

Reproduction repo link

https://github.com/privatenumber/issue-reproductions/tree/master/reproductions/nodejs/node/44316

Steps

  1. Create the following files:

node_modules/package/package.json:

{
	"exports": {
		"./*": "./*",
		"./internal/*": null
	}
}

node_modules/package/internal/file.js:

console.log('Accessed internal file!')

index.mjs:

import('package/internal/file.js').catch(() => {
	console.log('Fail: Single slash import')
})

import('package//internal/file.js').then(() => {
	console.log('Success: Double slash import')
})
  1. Run node ./index.mjs

How often does it reproduce? Is there a required condition?

Always. No environmental conditions. Just multiple slashes in import paths.

What is the expected behavior?

For import 'package//internal/file.js' to not resolve.

What do you see instead?

It resolves.

Additional information

No response

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