Zend-Mail remote code execution in zend-mail via Sendmail adapter
When using the zend-mail component to send email via the Zend\Mail\Transport\Sendmail transport, a malicious user may be able to inject arbitrary parameters to the system sendmail program. The attack is performed by providing additional quote characters within an address; when unsanitized, they can be interpreted as additional command line arguments, leading to the vulnerability.
The following example demonstrates injecting additional parameters to the sendmail binary via the From address:
use Zend\Mail;
$mail = new Mail\Message();
$mail->setBody('This is the text of the email.');
// inject additional parameters to sendmail command line
$mail->setFrom('"AAA\" params injection"@domain', 'Sender\'s name');
$mail->addTo('hacker@localhost', 'Name of recipient');
$mail->setSubject('TestSubject');
$transport = new Mail\Transport\Sendmail();
$transport->send($mail);
The attack works because zend-mail filters the email addresses using the RFC 3696 specification, where the string "AAA" params injection"@domain is considered a valid address. This validation is provided using the zend-validator component with the following parameters:
Zend\Validator\EmailAddress(
Zend\Validator\Hostname::ALLOW_DNS | Zend\Validator\Hostname::ALLOW_LOCAL
)
The above accepts local domain with any string specified by double quotes as the local part. While this is valid per RFC 3696, due to the fact that sender email addresses are provided to the sendmail binary via the command line, they create the vulnerability described above.
| Software | From | Fixed in |
|---|---|---|
zendframework / zend-mail
|
2.0.0 | 2.4.11 |
|
zendframework / zend-mail
|
2.5.0 | 2.7.2 |
- https://framework.zend.com/security/advisory/ZF2016-04
- https://github.com/FriendsOfPHP/security-advisories/blob/master/zendframework/zend-mail/ZF2016-04.yaml
- https://github.com/zendframework/zend-mail/commit/0a92d0b3a8b7d7c7659aa569f1a66a23d4ad51af
- https://github.com/zendframework/zend-mail/commit/7260c9768bf27c84f994c48698493fd1fa62fca3
- https://github.com/zendframework/zend-mail/commit/8d18478b40fdeef7239fb7ea203e072edcadbe54
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A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
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Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
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