Security Advisory: NPM ip package still incorrectly identifies some private IP addresses as public

[ouuan]

Description

The problem described in CVE-2023-42282 is not completely fixed in v2.0.1 and v1.1.9. The isPublic() function still identifies some private IP addresses as public. This may lead to SSRF attacks if the isPublic()/isPrivate()/isLoopback() functions are used to guard outgoing network requests.

PoC

See #143

• 127.1, 127.0.1, 127.00.0x1, 127.0.0x0.1
• 01200034567
• 012.1.2.3
• fe80::0001, 000:0:0000::01, 000:0:0000:0:000:0:00:001
• ::fFFf:127.0.0.1

Patches

No patch has been applied to the original package yet.

A patch has been proposed at #144.

Suggestions

The ip package is not actively maintained. The author is not responsive.

Users of this package are advised to use alternative packages with similar functions even if their use of the ip package is not affected by this vulnerability, in order to get better support and avoid other potential vulnerabilities and bugs.

Alternatively, users may check their usage of the isPublic()/isPrivate()/isLoopback() functions to see if they are used to guard sensitive network requests (e.g. check whether the IP address provided in user input is private or public before sending out a request to it). Also follow the Server Side Request Forgery Prevention - OWASP Cheat Sheet. It's likely that even a correctly implemented isPublic() function is not enough to prevent SSRF attacks.

[ouuan]

This is CVE-2024-29415 now.

[kth-tw]

Please fix this issue.

[vtulse]

Please fix this issue.

+1

[ouuan]

To be clear, GitHub identifies this as a high-severity issue in GHSA-2p57-rm9w-gvfp, but it depends on the actual use case. I think it's none or low in most cases, moderate in some cases, and rarely of high severity. You may read the suggestions above. However, I think the lack of maintenance of this package is arguably more severe than this CVE itself.

[ffraenz]

Unrelated to SSRF attacks, though behavior I did not expect: ip.isPublic('') evaluates to true because of the way it internally calls !ip.isPrivate('').

[jorenbroekema]

If someone finds a maintained alternative to this package, please let us know here :)!

[inquinity]

If someone finds a maintained alternative to this package, please let us know here :)!

npm is now using this package internally (instead of ip.js): https://www.npmjs.com/package/ip-address

[cbovis]

For anyone affected by this because of Storybook there's a discussion of relevance at storybookjs/storybook#26014. A PR has been merged to stop using the ip dependency but not yet released.

Edit: has been released in version 8.1.6

[pwilder-sig]

Won't help in every case but looks useful in mine: https://www.npmjs.com/package/is-in-subnet

Edit: Full disclosure, no association with this project and I'll note it has a much, much smaller user base. Caveat emptor.

Edit 2: Also some disagreement on what a "private subnet" is between libs so this may not be a 1:1 replacement.

[ffraenz]

@inquinity I was looking into the package you proposed and tried to come up with a replacement for ip.isPublic. However, the package seems to lack knowledge about special IPv4 subnets and private IPv6 addresses.

Here's what I came up with so far. Did I miss something?

Code not tested.

import ip from 'ip-address'

const ip4LoopbackSubnet = new ip.Address4('127.0.0.0/8')
const ip4LinkLocalSubnet = new ip.Address4('169.254.0.0/16')
const ip4PrivateASubnet = new ip.Address4('10.0.0.0/8')
const ip4PrivateBSubnet = new ip.Address4('172.16.0.0/12')
const ip4PrivateCSubnet = new ip.Address4('192.168.0.0/16')

const isPublicIp = (
  address: string
): boolean => {
  try {
    // Throws if address is not a valid IPv4 address
    const instance = new ip.Address4(address)
    // Exclude non-host IP addresses
    if (instance.subnetMask < 32) {
      return false
    }
    // Exclude non-public IPv4 addresses
    if (
      instance.isInSubnet(ip4LoopbackSubnet) ||
      instance.isInSubnet(ip4LinkLocalSubnet) ||
      instance.isInSubnet(ip4PrivateASubnet) ||
      instance.isInSubnet(ip4PrivateBSubnet) ||
      instance.isInSubnet(ip4PrivateCSubnet)
    ) {
      return false
    }
    return true
  } catch (error: unknown) {
    //
  }
  try {
    // Throws if address is not a valid IPv6 address
    const instance = new ip.Address6(address)
    // Exclude non-host IP addresses
    if (instance.subnetMask < 128) {
      return false
    }
    // Exclude non-public IPv6 addresses
    // TODO: Private IPv6 addresses
    if (instance.isLinkLocal() || instance.isLoopback()) {
      return false
    }
    return true
  } catch (error: unknown) {
    //
  }
  return false
}