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CVE-2016-10033 — The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow…

Key facts

CVE-2016-10033 is a Critical (9.8) vulnerability: The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow…. This entry ships a detection-only PoC and a Docker test lab. It is on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2025-07-07), confirming active exploitation in the wild.

Actively exploited — on the CISA KEV catalog

CVE-2016-10033 is listed on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2025-07-07), confirming exploitation in the wild. Federal remediation deadline: 2025-07-28. Prioritise patching and deploy the detection and prevention rules below.
CVE CVE-2016-10033
Severity Critical (9.8)
CISA KEV Actively exploited (added 2025-07-07)
Detection / prevention —
PoC poc.py
Source 2016/CVE-2016-10033/

Details

English | 한국어

Description

The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow remote attackers to pass extra parameters to the mail command and consequently execute arbitrary code via a \" (backslash double quote) in a crafted Sender property.

Vulnerability Details

Property Value
CVE ID CVE-2016-10033
CVSS Score 9.8

Proof of Concept

Download

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2016/CVE-2016-10033/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-2016-10033

# 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

  • http://packetstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.html
  • http://packetstormsecurity.com/files/140350/PHPMailer-Sendmail-Argument-Injection.html
  • http://seclists.org/fulldisclosure/2016/Dec/78
  • http://www.rapid7.com/db/modules/exploit/multi/http/phpmailer_arg_injection
  • http://www.securityfocus.com/archive/1/539963/100/0/threaded
  • http://www.securityfocus.com/bid/95108
  • http://www.securitytracker.com/id/1037533
  • https://developer.joomla.org/security-centre/668-20161205-phpmailer-security-advisory.html
  • https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18
  • https://github.com/PHPMailer/PHPMailer/wiki/About-the-CVE-2016-10033-and-CVE-2016-10045-vulnerabilities
  • https://legalhackers.com/advisories/PHPMailer-Exploit-Remote-Code-Exec-CVE-2016-10033-Vuln.html
  • https://www.drupal.org/psa-2016-004
  • https://www.exploit-db.com/exploits/40968/
  • https://www.exploit-db.com/exploits/40969/
  • https://www.exploit-db.com/exploits/40970/
  • https://www.exploit-db.com/exploits/40974/
  • https://www.exploit-db.com/exploits/40986/
  • https://www.exploit-db.com/exploits/41962/
  • https://www.exploit-db.com/exploits/41996/
  • https://www.exploit-db.com/exploits/42024/
  • https://www.exploit-db.com/exploits/42221/
  • http://packetstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.html
  • http://packetstormsecurity.com/files/140350/PHPMailer-Sendmail-Argument-Injection.html
  • http://seclists.org/fulldisclosure/2016/Dec/78
  • http://www.rapid7.com/db/modules/exploit/multi/http/phpmailer_arg_injection
  • http://www.securityfocus.com/archive/1/539963/100/0/threaded
  • http://www.securityfocus.com/bid/95108
  • http://www.securitytracker.com/id/1037533
  • https://developer.joomla.org/security-centre/668-20161205-phpmailer-security-advisory.html
  • https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18
  • https://github.com/PHPMailer/PHPMailer/wiki/About-the-CVE-2016-10033-and-CVE-2016-10045-vulnerabilities
  • https://legalhackers.com/advisories/PHPMailer-Exploit-Remote-Code-Exec-CVE-2016-10033-Vuln.html
  • https://www.drupal.org/psa-2016-004
  • https://www.exploit-db.com/exploits/40968/
  • https://www.exploit-db.com/exploits/40969/
  • https://www.exploit-db.com/exploits/40970/
  • https://www.exploit-db.com/exploits/40974/
  • https://www.exploit-db.com/exploits/40986/
  • https://www.exploit-db.com/exploits/41962/
  • https://www.exploit-db.com/exploits/41996/
  • https://www.exploit-db.com/exploits/42024/
  • https://www.exploit-db.com/exploits/42221/
  • https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2016-10033

Generated by PoC Generator on 2026-07-04T08:22:44.239267376

Frequently asked questions

What is CVE-2016-10033?

CVE-2016-10033 is a Critical (9.8) vulnerability: The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow…. This entry ships a detection-only PoC and a Docker test lab. It is on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2025-07-07), confirming active exploitation in the wild.

How do I detect CVE-2016-10033?

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-2016-10033?

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

Is CVE-2016-10033 actively exploited?

Yes. CVE-2016-10033 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, added 2025-07-07, which means it has been exploited in the wild. CISA set a federal remediation deadline of 2025-07-28. Prioritise patching and deploy the detection and prevention rules above.

For authorized security testing and research only. See the full source and NVD record.