Remote code execution in PHPMailer
Published 5 Mar 2020 · Updated 22 Oct 2025
Affected package
- Affected
- >=5.0.0 <5.2.18
- Fixed in
- 5.2.18
composer require phpmailer/phpmailer:^5.2.18Details
Impact
The mailSend function in the default 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.
Patches
Fixed in 5.2.18
Workarounds
Filter and validate user input before passing it to internal functions.
References
https://nvd.nist.gov/vuln/detail/CVE-2016-10033 Related to a follow-on issue in https://nvd.nist.gov/vuln/detail/CVE-2016-10045
For more information
If you have any questions or comments about this advisory:
- Open a private issue in the PHPMailer project
Is GHSA-5f37-gxvh-23v6 in any of your client repos?
Checking one package by hand is fine. Checking it across forty client projects is not. NPMscan reads the lockfiles in every GitHub repo you pick, finds each project with an affected phpmailer/phpmailer, and gives you the command that fixes it.
References
- Linkgithub.com/PHPMailer/PHPMailer/security/advisories/GHSA-5f37-gxvh-23v6
- Advisorynvd.nist.gov/vuln/detail/CVE-2016-10033
- Linkwww.exploit-db.com/exploits/42221
- Linkwww.exploit-db.com/exploits/42024
- Linkwww.exploit-db.com/exploits/41996
- Linkwww.exploit-db.com/exploits/41962
- Linkwww.exploit-db.com/exploits/40986
- Linkwww.exploit-db.com/exploits/40974
- Linkwww.exploit-db.com/exploits/40970
- Linkwww.exploit-db.com/exploits/40969
- Linkwww.exploit-db.com/exploits/40968
- Linkwww.drupal.org/psa-2016-004
- Linkwww.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2016-10033
- Linklegalhackers.com/advisories/PHPMailer-Exploit-Remote-Code-Exec-CVE-2016-10033-Vuln.html
- Linkgithub.com/PHPMailer/PHPMailer/wiki/About-the-CVE-2016-10033-and-CVE-2016-10045-vulnerabilities
- Linkgithub.com/PHPMailer/PHPMailer/releases/tag/v5.2.18
- Packagegithub.com/PHPMailer/PHPMailer
- Linkgithub.com/FriendsOfPHP/security-advisories/blob/master/phpmailer/phpmailer/CVE-2016-10033.yaml
- Linkdeveloper.joomla.org/security-centre/668-20161205-phpmailer-security-advisory.html
- Linkpacketstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.html
Advisory data from OSV.dev (opens OSV.dev in a new tab), refreshed daily.