Nginx < 1.7.4 SMTP STARTTLS Command Injection

critical Web Application Scanning Plugin ID 98957



Nginx < 1.7.4 SMTP STARTTLS Command Injection


According to the self-reported version in the server response header, the version of nginx installed on the remote host is 1.5.6 or higher, 1.6.x prior to 1.6.1, or 1.7.x prior to 1.7.4. It is, therefore, affected by a command injection vulnerability. A flaw exists in the function 'ngx_mail_smtp_starttls' within the file 'src/mail/ngx_mail_smtp_handler.c' whereby input to the STARTTLS command is not properly sanitized. This could allow a remote attacker in a privileged network position to obtain sensitive information by injecting commands into an SSL session. This issue is exploitable only when nginx is used as an SMTP proxy.

Note that the scanner has not tested for these issues but has instead relied only on the application's self-reported version number.


Upgrade to nginx 1.7.4 or later.

See Also

Plugin Details

Severity: Critical

ID: 98957

Type: remote

Published: 11/5/2018

Updated: 10/7/2021

Scan Template: pci, api, scan

Risk Information


Risk Factor: Low

Score: 2.5


Risk Factor: Medium

Base Score: 6.8

Vector: CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2014-3556


Risk Factor: Critical

Base Score: 9.8

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS Score Source: CVE-2014-3556

Vulnerability Information

CPE: cpe:2.3:a:nginx:nginx:*:*:*:*:*:*:*:*

Exploit Ease: No known exploits are available

Patch Publication Date: 12/29/2014

Vulnerability Publication Date: 12/29/2014

Reference Information

CVE: CVE-2014-3556