CVE DATABASE / CVE-2016-10033
CVE-2016-10033
PHPMailer Command Injection Vulnerability
Confirmed exploited in the wild. Added 2025-07-07.
Federal remediation due 2025-07-28.
Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Summary
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.
CVSS 3.1 breakdown
| Base score | 9.8 (CRITICAL) |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Attack vector | NETWORK |
| Attack complexity | LOW |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity | HIGH |
| Availability | HIGH |
Weakness type (CWE)
Affected products
Use our free CVE Lookup tool for the latest NVD record, or browse the full CISA KEV catalog.
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/
Data: NIST NVD + CISA KEV. NVD last modified 2026-04-21. Always verify against the vendor advisory before acting.