CVE-2016-10033: PHPMailer Command Injection Vulnerability

CISA Known Exploited Vulnerabilities

Name

PHPMailer Command Injection Vulnerability

Vendor

PHP

Product

PHPMailer

Added to the catalog

2025-07-07

Due date for US federal agencies

2025-07-28

Weaknesses

CWE-77, CWE-88

Catalog version

2026.10.30

PHPMailer contains a command injection vulnerability because it fails to sanitize user-supplied input. Specifically, this issue affects the 'mail()' function of 'class.phpmailer.php' script. An attacker can exploit this issue to execute arbitrary code within the context of the application. Failed exploit attempts will result in a denial-of-service condition.

Required action (CISA)

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Ransomware use: CISA does not mark known use of this vulnerability in ransomware campaigns.

Links in CISA's notes

• https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18
• https://github.com/advisories/GHSA-5f37-gxvh-23v6
• https://nvd.nist.gov/vuln/detail/CVE-2016-10033

Read on 2026-11-02T23:39:54.475Z under licence cisa-kev-cc0@b0067899 from https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

NVD analysis

Status

Analyzed

Published

2016-12-30T19:59:00.137

Last modified

2026-06-17T00:38:55.477

Weaknesses

CWE-88

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.

References

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

This product uses the NVD API but is not endorsed or certified by the NVD.

Read on 2026-11-02T23:41:35.381Z under licence nvd-api-terms-of-use@ff2a5288 from https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2016-10033

CVE record

Assigner

mitre

State

PUBLISHED

Published

2016-12-30T19:00:00.000Z

Updated

2025-10-21T23:55:47.202Z

Problem types

n/a

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.

References

• http://packetstormsecurity.com/files/140350/PHPMailer-Sendmail-Argument-Injection.html
• https://www.drupal.org/psa-2016-004
• 42221
• 40969
• 41962
• 40968
• https://legalhackers.com/advisories/PHPMailer-Exploit-Remote-Code-Exec-CVE-2016-10033-Vuln.html
• https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18
• 20161227 PHPMailer < 5.2.18 Remote Code Execution [updated advisory] [CVE-2016-10033]
• https://github.com/PHPMailer/PHPMailer/wiki/About-the-CVE-2016-10033-and-CVE-2016-10045-vulnerabilities
• http://packetstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.html
• 40974
• 40986
• 40970
• http://www.rapid7.com/db/modules/exploit/multi/http/phpmailer_arg_injection
• 41996
• 20161227 PHPMailer < 5.2.18 Remote Code Execution [CVE-2016-10033]
• 95108
• 1037533
• https://developer.joomla.org/security-centre/668-20161205-phpmailer-security-advisory.html
• 42024

Read on 2026-11-03T00:33:22.856Z under licence cve-terms-of-use@81bfa2f3 from https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2016/10xxx/CVE-2016-10033.json

Also known as / affected packages

Defensive techniques (MITRE D3FEND)

D3FEND maps these defensive techniques to the weakness (CWE) that NVD lists for this CVE, through the digital artifacts the weakness affects. D3FEND does not say they stop this vulnerability.

MITRE D3FEND™ knowledge graph. © 2025 The MITRE Corporation.
"The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use D3FEND for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." Terms: https://d3fend.mitre.org/tou/