ZeroDay Findings
Sign inSign up

Vulnerabilities

Vulnerability · CVE-2016-10033

PHPMailer Command Injection Vulnerability

Published Dec 30, 2016 · catalog updated Jun 16, 2026 · PHP PHPMailer

Patch now

CVE-2016-10033 is in the CISA known-exploited catalog, due Jul 28, 2025. Confirm PHP PHPMailer against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Severity
Critical9.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
99.71%
Remediation
Remediation guidance
Affected products
cpe joomla/joomla! · cpe phpmailer project/phpmailer · cpe wordpress/wordpress · vendor PHP PHPMailer

PHPMailer contains a command injection vulnerability because it fails to sanitize user-supplied input. Specifically, this issue affects the 'mail()' function of 'class.phpmailer.php' script. An attacker can exploit this issue to execute arbitrary code within the context of the application. Failed exploit attempts will result in a denial-of-service condition. Initial-access exploit intelligence.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe joomla/joomla!version unspecified
  • cpe phpmailer project/phpmailerversion unspecified
  • cpe wordpress/wordpressversion unspecified
  • vendor PHP PHPMailerversion unspecified

How to fix CVE-2016-10033

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2016-10033 is in the CISA known-exploited catalog, due Jul 28, 2025. Confirm PHP PHPMailer against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Affected version ranges are not on this record. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

What should an analyst verify?

CWE-77: Command Injection; CWE-88. EPSS 99.71%. The CISA KEV listing is the exploitation evidence. A public exploit reference is linked in Sources. That is not the same as confirmed exploitation. Use the source links for the original advisory.

Technology hubs

WordPress security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Dec 30, 2016 · Catalog

    Detected

    PHPMailer contains a command injection vulnerability because it fails to sanitize user-supplied input. Specifically, this issue affects the 'mail()' function of 'class.phpmailer.php' script. An attacker can exploit this issue to execute arbitrary code within the context of the application. Failed exploit attempts will result in a denial-of-service condition.

  2. Jul 7, 2025 · CISA KEV

    Known exploited

    Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

  3. Jul 28, 2025 · CISA KEV

    Remediation due

    Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

  4. Jun 16, 2026 · Catalog

    Updated

    PHPMailer contains a command injection vulnerability because it fails to sanitize user-supplied input. Specifically, this issue affects the 'mail()' function of 'class.phpmailer.php' script. An attacker can exploit this issue to execute arbitrary code within the context of the application. Failed exploit attempts will result in a denial-of-service condition.

Sources

  • CISA KEVConfirmed exploitationCVE-2016-10033

    PHPMailer contains a command injection vulnerability because it fails to sanitize user-supplied input. Specifically, this issue affects the 'mail()' function of 'class.phpmailer.php' script. An attacker can exploit this issue to execute arbitrary code within the context of the application. Failed exploit attempts will result in a denial-of-service condition.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2016-10033

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2016-10033

    30-day exploitation probability 99.7%

    first.org
  • Exploit DatabasePublic exploit reference41962

    Public archive entry. The exploit body is not stored here.

    exploit-db.com
  • Exploit DatabasePublic exploit reference41996

    Public archive entry. The exploit body is not stored here.

    exploit-db.com
  • Exploit DatabasePublic exploit reference42024

    Public archive entry. The exploit body is not stored here.

    exploit-db.com
  • Metasploit ModulesPublic exploit moduleexploit_multi/http/phpmailer_arg_injection

    Public module reference (manual). Module source is not copied into this catalog.

    rapid7.com
  • Metasploit ModulesPublic exploit moduleexploit_unix/webapp/wp_phpmailer_host_header

    Public module reference (average). Module source is not copied into this catalog.

    rapid7.com
  • NIST NVDVulnerability recordCVE-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 command and consequently execute arbitrary code via a \" (backslash double quote) in a crafted Sender property.

    nvd.nist.gov
  • Packet Storm SecurityCited referencehttp://packetstormsecurity.com/files/140291/PHPMailer-Remote-Code-Execution.html

    Packet Storm link already published on the finding.

    packetstormsecurity.com
  • Packet Storm SecurityCited referencehttp://packetstormsecurity.com/files/140350/PHPMailer-Sendmail-Argument-Injection.html

    Packet Storm link already published on the finding.

    packetstormsecurity.com
  • VulnCheck KEVConfirmed exploitationCVE-2016-10033

    PHPMailer contains a command injection vulnerability because it fails to sanitize user-supplied input. Specifically, this issue affects the 'mail()' function of 'class.phpmailer.php' script. An attacker can exploit this issue to execute arbitrary code within the context of the ap

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.