Server-side Request Forgery (SSRF)

Affecting netmask package, versions <2.0.1

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Overview

netmask is a library to parse IPv4 CIDR blocks.

Affected versions of this package are vulnerable to Server-side Request Forgery (SSRF). It incorrectly evaluates individual IPv4 octets that contain octal strings as left-stripped integers, leading to an inordinate attack surface on hundreds of thousands of projects that rely on netmask to filter or evaluate IPv4 block ranges, both inbound and outbound.

For example, a remote unauthenticated attacker can request local resources using input data 0177.0.0.1 (127.0.0.1), which netmask evaluates as the public IP 177.0.0.1. Contrastingly, a remote authenticated or unauthenticated attacker can input the data 0127.0.0.01 (87.0.0.1) as localhost, yet the input data is a public IP and can potentially cause local and remote file inclusion (LFI/RFI). A remote authenticated or unauthenticated attacker can bypass packages that rely on netmask to filter IP address blocks to reach intranets, VPNs, containers, adjacent VPC instances, or LAN hosts, using input data such as 012.0.0.1 (10.0.0.1), which netmask evaluates as 12.0.0.1 (public).

Remediation

Upgrade netmask to version 2.0.1 or higher.

References

CVSS Score

7.7
high severity
  • Attack Vector
    Network
  • Attack Complexity
    High
  • Privileges Required
    None
  • User Interaction
    None
  • Scope
    Unchanged
  • Confidentiality
    High
  • Integrity
    High
  • Availability
    Low
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L/E:P
Credit
Unknown
CVE
CVE-2021-28918 CVE-2021-29418
CWE
CWE-20 CWE-918
Snyk ID
SNYK-JS-NETMASK-1089716
Disclosed
29 Mar, 2021
Published
30 Mar, 2021