CVE-2016-10045: The isMail transport in PHPMailer before 5.2.20 might allow remote attackers to pass extra parameters to the m

Q: How do I fix CVE-2016-10045?

phpmailer: upgrade to 5.2.20; wordpress: upgrade to newer than 4.7; joomla\!: upgrade to newer than 3.6.5. Exact commands for each OS are on this page.

Q: Is CVE-2016-10045 being exploited?

CVE-2016-10045 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2016-10045 affect?

CVE-2016-10045 affects phpmailer, wordpress, joomla\!. Severity is critical (CVSS 9.8). The isMail transport in PHPMailer before 5.2.20 might allow remote attackers to pass extra parameters to the mail command and consequently execute arbitrary code by leveraging improper interaction between the escapeshellarg function and int

Q: How urgent is CVE-2016-10045?

Priority 69/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADEUPGRADEUPGRADE

CVE-2016-10045 is a critical-severity flaw (CVSS 9.8) affecting phpmailer, wordpress, joomla\!. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The isMail transport in PHPMailer before 5.2.20 might allow remote attackers to pass extra parameters to the mail command and consequently execute arbitrary code by leveraging improper interaction between the escapeshellarg function and internal escaping performed in the mail function in PHP. NOTE: this vulnerability exists because of an incorrect fix for CVE-2016-10033.

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	97.7% (top 1%)
CISA exploited list	No
Weakness	CWE-77
Published	2016-12-30
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: joomla · phpmailer project · wordpress

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2016-12-30 19:59 UTCPublished CVE record published
2026-06-17 00:38 UTCUpdated Record last modified

phpmailer project phpmailer UPGRADE

Affected: < 5.2.20

Fixed in: 5.2.20

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy phpmailer || rpm -q phpmailer || phpmailer --version

2. UPGRADE to 5.2.20 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade phpmailer

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade phpmailer

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

wordpress wordpress UPGRADE

Affected: <= 4.7

Fixed in: newer than 4.7

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy wordpress || rpm -q wordpress || wordpress --version

2. UPGRADE to newer than 4.7 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade wordpress

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade wordpress

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

joomla joomla\! UPGRADE

Affected: >= 1.5.0 and <= 3.6.5

Fixed in: newer than 3.6.5

Safe to downgrade to: a release before 1.5.0

1. Check installed version

apt-cache policy joomla || rpm -q joomla || joomla --version

2. UPGRADE to newer than 3.6.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade joomla

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade joomla

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.5.0 (Debian / Ubuntu)

apt-cache madison joomla sudo apt install joomla=<VERSION_BEFORE_1.5.0> sudo apt-mark hold joomla

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list joomla sudo dnf downgrade joomla-<VERSION_BEFORE_1.5.0> sudo dnf versionlock add joomla

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: PHPMailer < 5.2.20 - Remote Code Execution
Exploit-DB: PHPMailer < 5.2.20 / SwiftMailer < 5.4.5-DEV / Zend Framework / zend-mail < 2.4.11 - 'AIO' 'PwnScriptum' Remote Code Exe
Exploit-DB: PHPMailer < 5.2.20 with Exim MTA - Remote Code Execution
Metasploit: PHPMailer Sendmail Argument Injection

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2016-10045?

phpmailer: upgrade to 5.2.20; wordpress: upgrade to newer than 4.7; joomla\!: upgrade to newer than 3.6.5. Exact commands for each OS are on this page.

Is CVE-2016-10045 being exploited?

CVE-2016-10045 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2016-10045 affect?

CVE-2016-10045 affects phpmailer, wordpress, joomla\!. Severity is critical (CVSS 9.8). The isMail transport in PHPMailer before 5.2.20 might allow remote attackers to pass extra parameters to the mail command and consequently execute arbitrary code by leveraging improper interaction between the escapeshellarg function and int

How urgent is CVE-2016-10045?

Priority 69/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

WordPress vulnerabilities · Joomla vulnerabilities · PHP vulnerabilities

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References

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