CVE-2014-3556

Name: CVE-2014-3556
Creator: NVD / NIST
Published: 2014-12-29T20:59:03.943+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

UnknownEPSS 7.83%

Last modified Jun 17, 2026

CVE-2014-3556 is a vulnerability of currently unknown severity. The STARTTLS implementation in mail/ngx_mail_smtp_handler.c in the SMTP proxy in nginx 1.5.x and 1.6.x before 1.6.1 and 1.7.x before 1.7.4 does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted SMTP sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack, a similar issue to CVE-2011-0411.. EPSS estimates a 7.83% chance of exploitation in the next 30 days.

Description

The STARTTLS implementation in mail/ngx_mail_smtp_handler.c in the SMTP proxy in nginx 1.5.x and 1.6.x before 1.6.1 and 1.7.x before 1.7.4 does not properly restrict I/O buffering, which allows man-in-the-middle attackers to insert commands into encrypted SMTP sessions by sending a cleartext command that is processed after TLS is in place, related to a "plaintext command injection" attack, a similar issue to CVE-2011-0411.

Metrics

EPSS Probability

7.83%

93.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-77

Affected Software

Vendor	Product	Versions
F5	Nginx	>= 1.5.6, < 1.6.1
F5	Nginx	>= 1.7.0, < 1.7.4

References

http://mailman.nginx.org/pipermail/nginx-announce/2014/000144.htmlPatch, Vendor Advisory
http://marc.info/?l=bugtraq&m=142103967620673&w=2Issue Tracking, Third Party Advisory
http://nginx.org/download/patch.2014.starttls.txtPatch, Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1126891Issue Tracking, Third Party Advisory
http://mailman.nginx.org/pipermail/nginx-announce/2014/000144.htmlPatch, Vendor Advisory
http://marc.info/?l=bugtraq&m=142103967620673&w=2Issue Tracking, Third Party Advisory
http://nginx.org/download/patch.2014.starttls.txtPatch, Vendor Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1126891Issue Tracking, Third Party Advisory

Timeline

Published: Dec 29, 2014
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2014-3556?

How severe is CVE-2014-3556?

Severity scoring for CVE-2014-3556 is pending analysis. The EPSS model estimates a 7.83% probability of exploitation in the next 30 days.

How do I fix CVE-2014-3556?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2014-3556?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST