CVE-2016-10033
The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow remote attackers to pass extra parameters to the mail…
- 9.8CriticalCVSS base score
- 99.7%Exploitation in 30 daysEPSS · top 0.1% of all CVEs
- YesKnown exploitedin CISA's KEV since 7 Jul 2025
- 12Public exploitsMetasploit, Nuclei and Exploit-DB
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.
Exploited in the wild
CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as PHPMailer Command Injection Vulnerability.
- Added
- 7 Jul 2025
- Fix due (US federal)
- 28 Jul 2025
- Used by ransomware
- Not known
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
ENISA's EU Vulnerability Database lists it as exploited, from CISA's KEV, since 7 Jul 2025.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. The public collections list 2 Metasploit modules, a Nuclei template and 9 Exploit-DB entries for it. 9 references of the record are tagged as an exploit. CISA's SSVC rates its exploitation: it is being exploited.
Show the exploits21
Metasploit modules2 modules
- WordPress PHPMailer Host Header Command Injection (Metasploit module) (opens in a new tab)
exploit/unix/webapp/wp_phpmailer_host_headerRank averagedisclosed 3 May 2017
- PHPMailer Sendmail Argument Injection (Metasploit module) (opens in a new tab)
exploit/multi/http/phpmailer_arg_injectionRank manualdisclosed 26 Dec 2016
Nuclei templates1 template
- WordPress PHPMailer < 5.2.18 - Remote Code Execution (Nuclei template) (opens in a new tab)
http/cves/2016/CVE-2016-10033.yamlSeverity critical
Exploit-DB9 entries
- PHPMailer < 5.2.20 with Exim MTA - Remote Code Execution (Exploit-DB entry) (opens in a new tab)
EDB-ID 42221webapps, phppublished 21 Jun 2017Not verified
- WordPress Plugin PHPMailer 4.6 - Host Header Command Injection (Metasploit) (Exploit-DB entry) (opens in a new tab)
EDB-ID 42024remote, phppublished 17 May 2017Verified
- Vanilla Forums < 2.3 - Remote Code Execution (Exploit-DB entry) (opens in a new tab)
EDB-ID 41996remote, phppublished 11 May 2017Not verified
- WordPress Core 4.6 - Remote Code Execution (Exploit-DB entry) (opens in a new tab)
EDB-ID 41962webapps, linuxpublished 3 May 2017Not verified
- PHPMailer < 5.2.20 / SwiftMailer < 5.4.5-DEV / Zend Framework / zend-mail < 2.4.11 - 'AIO' 'PwnScriptum' Remote Code Execution (Exploit-DB entry) (opens in a new tab)
EDB-ID 40986webapps, phppublished 2 Jan 2017Not verified
- PHPMailer < 5.2.18 - Remote Code Execution (Exploit-DB entry) (opens in a new tab)
EDB-ID 40974webapps, phppublished 29 Dec 2016Not verified
- PHPMailer < 5.2.20 - Remote Code Execution (Exploit-DB entry) (opens in a new tab)
EDB-ID 40969webapps, phppublished 27 Dec 2016Not verified
- PHPMailer < 5.2.18 - Remote Code Execution (Exploit-DB entry) (opens in a new tab)
EDB-ID 40968webapps, phppublished 26 Dec 2016Verified
- PHPMailer < 5.2.18 - Remote Code Execution (Exploit-DB entry) (opens in a new tab)
EDB-ID 40970webapps, phppublished 25 Dec 2016Not verified
References tagged exploit9 references
- 42221 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 40969 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 41962 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 40968 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 40974 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 40986 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 40970 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 41996 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 42024 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
Modules, templates and exploits as listed by the Metasploit Framework (BSD-3-Clause), ProjectDiscovery's Nuclei templates (MIT) and the Exploit Database (GPLv2), read once a day. Where the data comes from
Timeline
ID reserved
By mitre
- 8 days later
· 8 days later
Published
- 9 years later
· 9 years later
Added to CISA KEV
Known exploited in the wild
- 4 months later
· 4 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Analyzed | 3.1 | Critical9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 99.7% · top 0.1% of all CVEs (9 Nov 2026)
- CISA SSVC
- Exploitation: active · Automatable: yes · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.8.
Affected products
n/a
- affected n/a
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Packagistphpmailer/phpmailerGHSA-5f37-gxvh-23v6 (opens in a new tab)
References
22
- http://packetstormsecurity.com/files/140350/PHPMailer-Sendmail-Argument-Injection.html (opens in a new tab)x_refsource_MISCx_transferred
- https://www.drupal.org/psa-2016-004 (opens in a new tab)x_refsource_CONFIRMx_transferred
- 42221 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 40969 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 41962 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 40968 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- https://legalhackers.com/advisories/PHPMailer-Exploit-Remote-Code-Exec-CVE-2016-10033-Vuln.html (opens in a new tab)x_refsource_MISCx_transferred
- https://github.com/PHPMailer/PHPMailer/releases/tag/v5.2.18 (opens in a new tab)x_refsource_CONFIRMx_transferred
- 20161227 PHPMailer < 5.2.18 Remote Code Execution [updated advisory] [CVE-2016-10033] (opens in a new tab)mailing-listx_refsource_BUGTRAQx_transferred
- https://github.com/PHPMailer/PHPMailer/wiki/About-the-CVE-2016-10033-and-CVE-2016-10045-vulnerabilities (opens in a new tab)x_refsource_CONFIRMx_transferred
- http://packetstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.html (opens in a new tab)x_refsource_MISCx_transferred
- 40974 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 40986 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 40970 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- http://www.rapid7.com/db/modules/exploit/multi/http/phpmailer_arg_injection (opens in a new tab)x_refsource_MISCx_transferred
- 41996 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- 20161227 PHPMailer < 5.2.18 Remote Code Execution [CVE-2016-10033] (opens in a new tab)mailing-listx_refsource_FULLDISCx_transferred
- 95108 (opens in a new tab)vdb-entryx_refsource_BIDx_transferred
- 1037533 (opens in a new tab)vdb-entryx_refsource_SECTRACKx_transferred
- https://developer.joomla.org/security-centre/668-20161205-phpmailer-security-advisory.html (opens in a new tab)x_refsource_CONFIRMx_transferred
- 42024 (opens in a new tab)exploitx_refsource_EXPLOIT-DBx_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2016-10033 (opens in a new tab)government-resource
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- CISA KEV catalog (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2020-0331 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-5f37-gxvh-23v6 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2016-10033)Record last updated .