CVE-2014-3556

medium

Published 2014-12-29 · Modified 2026-05-06

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CVSS v3

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CVSS v4 NEW

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not yet in upstream

VIR risk

6.8

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.

Predictions

Exploit likelihood

20%

Patch ETA

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Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

OS impact

Debian Fixed 5 releases

Version	Status	Fixed in
trixie	Fixed	`1.6.1-1`
sid	Fixed	`1.6.1-1`
forky	Fixed	`1.6.1-1`
bullseye	Fixed	`1.6.1-1`
bookworm	Fixed	`1.6.1-1`

Application impact

Vendor	Product	Versions	Fixed
f5	nginx	`{"startIncluding":"1.5.6","endExcluding":"1.6.1"}`	`1.6.1`
nginx	nginx	`{"startIncluding":"1.5.6","endExcluding":"1.6.1"}`	`1.6.1`
nginx	nginx	`{"startIncluding":"1.7.0","endExcluding":"1.7.4"}`	`1.7.4`

References

CWEs

CWE-77

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.