CVE-2014-3556
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.
Key facts
- CVSS score
- 6.8 (v2.0)
- Severity
- MEDIUM
- CVSS vector
AV:N/AC:M/Au:N/C:P/I:P/A:P- Weakness (CWE)
- CWE-77
- EPSS score
- 7.8% (95th percentile)
- In CISA KEV
- No
- In EU EUVD
- Yes (EUVD-2014-3539)
- Published
- December 29, 2014
- NVD last modified
- June 17, 2026
- Status
- Modified
EU Vulnerability Database (EUVD)
This vulnerability is also tracked by ENISA as EUVD-2014-3539 in the EU Vulnerability Database. Last updated in EUVD on August 6, 2024.
View on the EU Vulnerability DatabaseAffected products
- f5 / nginx
References
- http://mailman.nginx.org/pipermail/nginx-announce/2014/000144.html(Patch, Vendor Advisory)
- http://marc.info/?l=bugtraq&m=142103967620673&w=2(Issue Tracking, Third Party Advisory)
- http://nginx.org/download/patch.2014.starttls.txt(Patch, Vendor Advisory)
- https://bugzilla.redhat.com/show_bug.cgi?id=1126891(Issue Tracking, Third Party Advisory)
Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS
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