CVE-2014-3556
MEDIUMEPSS 94th pctlDescription
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.
How to fix
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v2 Vector
No CVSS vector data available.
Exploit Intelligence
High risk: more likely to be exploited than 94% of all known CVEs.
References
Related Vulnerabilities
Other CWE-77 (Command Injection) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-3400 | Critical | 10.0 | 100% | KEV + Ransom | - |
| CVE-2024-21887 | Critical | 9.1 | 100% | KEV + Ransom | - |
| CVE-2023-1671 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2023-1389 | High | 8.8 | 100% | KEV | Fix |
| CVE-2021-1498 | Critical | 9.8 | 100% | KEV | Fix |
| CVE-2012-1823 | Critical | 9.8 | 100% | KEV | Fix |
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Start freeThis product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-05-06.