Skip to content
Fencer Intel
critical 9.8

CVE-2016-10033 kev in the critical feed json

Remote code execution in PHPMailer

published 2016-12-30 9 y ago modified 2026-06-17 4 mo ago also GHSA-5f37-gxvh-23v6 , EUVD-2020-0331

cvss
9.8
version 3.1, CNA
cisa kev
Exploited
added 2025-07-07
epss
99.7%
EPSS 99.7% chance of exploitation in 30 days, percentile 99.9%
public exploits
11
Metasploit, Exploit-DB, plus a Nuclei check

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.

Patch / fix

cisa 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.

  • packagist phpmailer/phpmailer 5.2.18
  • phpmailer_project phpmailer 5.2.18
  • libphp-phpmailer Debian 14, Debian 13, Debian 12 5.2.14+dfsg-2.1

debian advisories DEBIAN-CVE-2016-10033

  • libphp-phpmailer Ubuntu Pro 16.04 LTS 5.2.14+dfsg-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2016-10033

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • php-phpmailer Alpine 3.3, Alpine 3.2 5.2.4-r0
  • php5-phpmailer Alpine 3.4 5.2.0-r1
  • php5-phpmailer Alpine 3.5 5.2.4-r1

alpine advisories ALPINE-CVE-2016-10033

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • wordpress Arch Linux 4.7.1-1

arch linux advisories AVG-142

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-10033 updated cvss 9.8

phpmailer: Parameter injection via mail() function

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Timeline

  1. First public exploit (EDB-40970)
  2. Published
  3. Added to CISA KEV
  4. CISA SSVC: exploitation active
  5. CISA patch deadline

Known exploited

Added
16 mo ago
Patch by
2025-07-28 (15 mo ago)
Ransomware
Not known
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.
Vendor, product
PHP, PHPMailer
CISA name
PHPMailer Command Injection Vulnerability

ATT&CK techniques

How it is exploited and what it leads to, in MITRE ATT&CK terms.

  • T1190 Exploit Public-Facing Application exploitation
  • T1059.004 Unix Shell primary impact

kev release 2025-07-28, att&ck v16.1. KEV to ATT&CK mappings by the MITRE Center for Threat-Informed Defense (Mappings Explorer, Apache-2.0). © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. Terms of use

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
15 mo ago

Exploit prediction

99.71% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • Metasploit exploit/unix/webapp/wp_phpmailer_host_header WordPress PHPMailer Host Header Command Injection metasploit exploit, average rank, 2017-05-03
  • Metasploit exploit/multi/http/phpmailer_arg_injection PHPMailer Sendmail Argument Injection metasploit exploit, manual rank, 2016-12-26
  • EDB-42221 PHPMailer < 5.2.20 with Exim MTA - Remote Code Execution webapps, 2017-06-21
  • EDB-42024 WordPress Plugin PHPMailer 4.6 - Host Header Command Injection (Metasploit) remote, 2017-05-17
  • EDB-41996 Vanilla Forums < 2.3 - Remote Code Execution remote, 2017-05-11
  • EDB-41962 WordPress Core 4.6 - Remote Code Execution webapps, 2017-05-03
  • EDB-40986 PHPMailer < 5.2.20 / SwiftMailer < 5.4.5-DEV / Zend Framework / zend-mail < 2.4.11 - 'AIO' 'PwnScriptum' Remote Code Execution webapps, 2017-01-02
  • EDB-40974 PHPMailer < 5.2.18 - Remote Code Execution webapps, 2016-12-29
  • EDB-40970 PHPMailer < 5.2.18 - Remote Code Execution webapps, 2016-12-25
  • EDB-40969 PHPMailer < 5.2.20 - Remote Code Execution webapps, 2016-12-27
  • EDB-40968 PHPMailer < 5.2.18 - Remote Code Execution webapps, 2016-12-26
  • Nuclei template WordPress PHPMailer < 5.2.18 - Remote Code Execution nuclei detection template
  • legalhackers.com https://legalhackers.com/advisories/PHPMailer-Exploit-Remote-Code-Exec-CVE-2016-10033-Vuln.html referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/140350/PHPMailer-Sendmail-Argument-Injection.html referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.html referenced PoC, tagged "exploit" by a source, unverified
  • rapid7.com http://www.rapid7.com/db/modules/exploit/multi/http/phpmailer_arg_injection referenced PoC, tagged "exploit" by a source, unverified
  • securityfocus.com http://www.securityfocus.com/bid/95108 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:H

Affected packages

ecosystem package affected fixed in
packagist phpmailer/phpmailer
>=5.0.0, <5.2.18
5.2.18

Classification

Weakness
  • CWE-88 Improper Neutralization of Argument Delimiters in a Command
  • CWE-77 Improper Neutralization of Special Elements used in a Command
Technology feeds

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.