CVE-2026-78003 — The Mailgun for WordPress plugin for WordPress is vulnerable to Server-Side Request…¶
Key facts
CVE-2026-78003 is a Critical (9.8) vulnerability: The Mailgun for WordPress plugin for WordPress is vulnerable to Server-Side Request…. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-78003 |
| Severity | Critical (9.8) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-78003/ |
Details¶
English | 한국어
Description¶
The Mailgun for WordPress plugin for WordPress is vulnerable to Server-Side Request Forgery (SSRF) via path traversal in versions up to and including 2.2.0. This is due to insufficient input validation in the add_list() function, which accepts user-controlled array keys from $_POST['addresses'], passes them through sanitize_text_field(). This makes it possible for unauthenticated attackers to make authenticated POST requests to any Mailgun API endpoint using the WordPress site's API key, including creating inbound email-forwarding routes that can intercept password reset emails, leading to administrator account takeover.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-78003 |
| Type | SSRF |
| CVSS Score | 9.8 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-78003/poc.py
Usage¶
# Run PoC against target
python3 poc.py --target <TARGET_URL>
# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>
⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.
Test Lab¶
This repository includes a Docker-based test environment with both vulnerable and patched applications.
Quick Start¶
# Clone and navigate to CVE directory
cd CVE-2026-78003
# Start both applications
docker-compose up -d
# Run tests
./run-tests.sh # Linux/Mac
./run-tests.ps1 # Windows PowerShell
Application Endpoints¶
| Application | URL | Status |
|---|---|---|
| Vulnerable App | http://localhost:8080 | Shows vulnerability |
| Patched App | http://localhost:8081 | Demonstrates fix |
Directory Structure¶
├── README.md # English documentation
├── README_KO.md # Korean documentation
├── poc.py # PoC detection script
├── docker-compose.yml # Container orchestration
├── run-tests.sh # Linux/Mac test runner
├── run-tests.ps1 # Windows test runner
├── vulnerable-app/ # Vulnerable version
│ ├── app.py
│ ├── Dockerfile
│ └── requirements.txt
└── patched-app/ # Fixed version
├── app.py
├── Dockerfile
└── requirements.txt
References¶
- https://plugins.trac.wordpress.org/browser/mailgun/tags/2.1.10/mailgun.php#L259
- https://plugins.trac.wordpress.org/browser/mailgun/tags/2.1.10/mailgun.php#L323
- https://plugins.trac.wordpress.org/browser/mailgun/tags/2.1.10/mailgun.php#L331
- https://plugins.trac.wordpress.org/browser/mailgun/tags/2.1.10/mailgun.php#L557
- https://plugins.trac.wordpress.org/browser/mailgun/trunk/mailgun.php#L259
- https://plugins.trac.wordpress.org/browser/mailgun/trunk/mailgun.php#L323
- https://plugins.trac.wordpress.org/browser/mailgun/trunk/mailgun.php#L331
- https://plugins.trac.wordpress.org/browser/mailgun/trunk/mailgun.php#L557
- https://www.wordfence.com/threat-intel/vulnerabilities/id/110e888d-69fc-4682-b908-2b62288c5227?source=cve
Generated by PoC Generator on 2026-08-22T18:51:05.174809811
Frequently asked questions¶
What is CVE-2026-78003?¶
CVE-2026-78003 is a Critical (9.8) vulnerability: The Mailgun for WordPress plugin for WordPress is vulnerable to Server-Side Request…. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-78003?¶
Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.
How do I block or mitigate CVE-2026-78003?¶
Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.
For authorized security testing and research only. See the full source and NVD record.