Vulnerability report

Exploited in the wild High confidence Not in CISA KEV

CVE-2023-6875

POST SMTP – The #1 WordPress SMTP Plugin with Advanced Email Logging and Delivery Failure Notifications

WPExperts.io / POST SMTP – The #1 WordPress SMTP Plugin with Advanced Email Logging and Delivery Failure Notifications · * to <= 2.8.7

Watch CVE-2023-6875 Browse KEV feed
Severity
CVSS 9.8 · Critical
Confidence
High
Exploit status
Exploited in the wild
EPSS
90.3%
First observed
—
Last observed
—

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2023-6875 is an unauthenticated vulnerability affecting WPExperts.io POST SMTP – The #1 WordPress SMTP Plugin with Advanced Email Logging and.... The POST SMTP Mailer – Email log, Delivery Failure Notifications...

Is it exploited?

Yes. Previdian tracks this CVE as a known exploited vulnerability. Confidence is high. Also confirmed by third-party sources.

Who is affected?

WPExperts.io / POST SMTP – The #1 WordPress SMTP Plugin with Advanced Email Logging and Delivery Failure Notifications * to <= 2.8.7.

What should we do?

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

Overview

POST SMTP – The #1 WordPress SMTP Plugin with Advanced Email Logging and Delivery Failure Notifications

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.

This makes it possible for unauthenticated attackers to reset the API key used to authenticate to the mailer and view logs, including password reset emails, allowing site takeover.

wpexpertsio Affected
POST SMTP – The #1 WordPress SMTP Plugin with Advanced Email Logging and Delivery Failure Notifications
Through 2.8.7
Published
11 Jan 2024
Exploitation Reported
25 Apr 2025
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

wordpress nuclei_scanner

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

The Shadowserver

Recorded 25 Apr 2025

A trusted third party reported exploitation.

Proof of concept available

GitHub

Recorded 13 Jan 2024

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
The Shadowserver First 2026-06-04 00:00 UTC

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
0
0
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2023/CVE-2023-6875.yaml 25 Apr 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

90.3%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Authorization Bypass Through User-Controlled Key CWE-639 Missing Authorization CWE-862

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

WordPress POST SMTP Mailer <= 2.8.7 - Authorization Bypass

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. 14:20 UTC

    Public PoC available

    Public proof-of-concept code published

  2. 00:00 UTC

    Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  3. 00:00 UTC

    Nuclei template available

    Scanner coverage available

  4. 08:33 UTC

    CVE published

    Vulnerability disclosed publicly

  5. 18:36 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2023-6875

Sample API response 
{
  "cve_id": "CVE-2023-6875",
  "confidence": "High",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.90339,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "attempts": 0, "sensors": 0 }
}