PHPMailer Command Injection Vulnerability

Exploited · KEV 2025-07-07Metasploit moduleCVE-2016-10033CWE-77CWE-88

Exploited since 2025-07-07. No WAF vendor names it yet. Our CRS test: not blocked.

Edge rules

0/8

Our test

Not blocked

CVSS

9.8

EPSS

99.7% Top 0.1%

Posts, 14d

Published

2016-12-30

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.

Edge coverage

Claimed by vendors

CloudflareBefore feed historyOlder than its feedWe measured: passed AWSBefore feed historyOlder than its feedWe measured: passed Microsoft AzureNo public claimNot named Google CloudBefore feed historyOlder than its feedWe measured: passed FastlyBefore feed historyOlder than its feed F5Before feed historyOlder than its feed AkamaiNo public sourceNo public changelog OWASP CRSBefore feed historyOlder than its feed

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AI · answers from this page

Ask about CVE-2016-10033: who's covered, what to patch first, how vendors compare. I cite sources and won't help with attacks.

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Severity, decoded

CVSS 3.1

9.8Critical

Critical · 9.8 / 10

Exploitable over the network, with no privileges and no user interaction, leading to full loss of confidentiality, integrity and availability.

Over the internetNo login neededNo user actionWorks reliablyFull compromise

How the score is built8 metrics

Attack vectorAn attacker can reach it over the internet; no access to your network needed.
Network
Attack complexityNo special conditions are needed; the attack works reliably.
Low
Privileges requiredNo account or login is needed.
None
User interactionNo one has to click or open anything; the attack works on its own.
None
ScopeThe damage stays within the vulnerable component.
Unchanged
Confidentiality impactAn attacker can read all data the affected component holds, or the most sensitive parts of it.
High
Integrity impactAn attacker can change any data or files the affected component protects.
High
Availability impactAn attacker can take the component down completely or keep it from serving anyone.
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CISA's assessmentSSVC, from the CVE record

ExploitationActive

Attackers are exploiting this in the wild.

AutomatableYes

Attackers can script the attack end to end and hit many targets at once.

Technical impactTotal

A successful attack gives full control over the affected software or all of its data.

Public exploits

12 found

2 Metasploit9 Exploit-DB1 Scanner template0 GitHub PoCs

MetasploitWordPress PHPMailer Host Header Command Injection2017-05-03 · exploit · rank Average · has check
MetasploitPHPMailer Sendmail Argument Injection2016-12-26 · exploit · rank Manual
Exploit-DBPHPMailer < 5.2.20 with Exim MTA - Remote Code Execution2017-06-21 · webapps · php
Exploit-DBWordPress Plugin PHPMailer 4.6 - Host Header Command Injection (Metasploit)2017-05-17 · remote · php · verified
Exploit-DBVanilla Forums < 2.3 - Remote Code Execution2017-05-11 · remote · php
Exploit-DBWordPress Core 4.6 - Remote Code Execution2017-05-03 · webapps · linux
Exploit-DBPHPMailer < 5.2.20 / SwiftMailer < 5.4.5-DEV / Zend Framework / zend-mail < 2.4.11 - 'AIO' 'PwnScriptum' Remote Code Execution2017-01-02 · webapps · php
NucleiCVE-2016-10033.yamldetection template, replayed in our lab

Links are to third-party code: never run it outside an isolated lab.

Timeline

2016-12-25
Exploit published on Exploit-DB
PHPMailer < 5.2.18 - Remote Code Execution
2016-12-26
Metasploit module published
PHPMailer Sendmail Argument Injection
2016-12-30
CVE published
CVE List
2025-07-07
Added to CISA KEV
Confirmed exploitation in the wild
2026-11-02
Our test: OWASP Core Rule Set let it through
paranoia level 1, anomaly threshold 5, default CRS settings
2026-11-02
Our test: OWASP Core Rule Set blocked part of it
paranoia level 2, anomaly threshold 5, default CRS settings