nginx: SMTP STARTTLS plaintext injection flaw
Published Dec 29, 2014
6.8
MEDIUMCVSS 2.0
EPSS 7.83%
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.
Affected products
No data.
No data.
Red Hat Software Collections
nginx14-nginx
Not affected
Red Hat Software Collections
nginx16-nginx
Affected
| Product | Package | State | Advisory |
|---|---|---|---|
| Red Hat Software Collections | nginx14-nginx | Not affected | n/a |
| Red Hat Software Collections | nginx16-nginx | Affected | n/a |
No package ranges for this CVE.
Remediation
Red Hat statement
This issue did not affect the versions of nginx as shipped with Red Hat Software Collections 1 for Red Hat Enterprise Linux 6 and 7.
Metrics
No CVSS v4.0 score for this CVE.
No CVSS v3.1 score for this CVE.
No CVSS v3.0 score for this CVE.
AV:N/AC:M/Au:N/C:P/I:P/A:P
This CVE is not in the KEV list.
No CISA SSVC assessment for this CVE yet.
Estimated probability of exploitation in the wild in the next 30 days (FIRST EPSS). As of Oct 1, 2026.
Score over time
2022–2026- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Percentile over time
- EPSS v2
- EPSS v3
- EPSS v4
- EPSS v5
Table of values (42 key points)
Flat stretches are collapsed; showing up to 120 newest points.
| Date | Score | Percentile | Model |
|---|---|---|---|
| Oct 1, 2026 | 7.83% (0.07832) | 94.50th | v5 (v2026.06.15) |
| Jun 15, 2026 | 7.83% (0.07832) | 93.90th | v5 (v2026.06.15) |
| Mar 4, 2026 | 48.17% (0.48169) | 97.66th | v4 (v2025.03.14) |
| Mar 1, 2026 | 20.58% (0.20584) | 95.49th | v4 (v2025.03.14) |
| Feb 4, 2026 | 48.17% (0.48169) | 97.64th | v4 (v2025.03.14) |
| Feb 1, 2026 | 20.58% (0.20584) | 95.45th | v4 (v2025.03.14) |
| Jan 4, 2026 | 48.17% (0.48169) | 97.62th | v4 (v2025.03.14) |
| Jan 1, 2026 | 20.58% (0.20584) | 95.43th | v4 (v2025.03.14) |
| Dec 28, 2025 | 48.17% (0.48169) | 97.62th | v4 (v2025.03.14) |
| Dec 27, 2025 | 42.43% (0.42434) | 97.34th | v4 (v2025.03.14) |
| Dec 4, 2025 | 48.17% (0.48169) | 97.59th | v4 (v2025.03.14) |
| Dec 1, 2025 | 20.58% (0.20584) | 95.38th | v4 (v2025.03.14) |
| Nov 4, 2025 | 48.17% (0.48169) | 97.59th | v4 (v2025.03.14) |
| Nov 1, 2025 | 20.58% (0.20584) | 95.36th | v4 (v2025.03.14) |
| Oct 28, 2025 | 48.17% (0.48169) | 97.58th | v4 (v2025.03.14) |
| Oct 27, 2025 | 42.43% (0.42434) | 97.30th | v4 (v2025.03.14) |
| Oct 4, 2025 | 48.17% (0.48169) | 97.64th | v4 (v2025.03.14) |
| Oct 1, 2025 | 20.58% (0.20584) | 95.41th | v4 (v2025.03.14) |
| Sep 4, 2025 | 42.43% (0.42434) | 97.38th | v4 (v2025.03.14) |
| Sep 1, 2025 | 16.75% (0.16751) | 94.72th | v4 (v2025.03.14) |
| Aug 5, 2025 | 42.43% (0.42434) | 97.34th | v4 (v2025.03.14) |
| Aug 1, 2025 | 16.75% (0.16751) | 94.70th | v4 (v2025.03.14) |
| Jul 30, 2025 | 42.43% (0.42434) | 97.34th | v4 (v2025.03.14) |
| Jul 4, 2025 | 48.17% (0.48169) | 97.60th | v4 (v2025.03.14) |
| Jul 1, 2025 | 20.58% (0.20584) | 95.32th | v4 (v2025.03.14) |
| Jun 6, 2025 | 48.17% (0.48169) | 97.57th | v4 (v2025.03.14) |
| Jun 1, 2025 | 20.49% (0.20492) | 95.26th | v4 (v2025.03.14) |
| May 25, 2025 | 37.14% (0.37142) | 96.95th | v4 (v2025.03.14) |
| May 18, 2025 | 48.17% (0.48169) | 97.57th | v4 (v2025.03.14) |
| May 5, 2025 | 31.14% (0.31142) | 96.46th | v4 (v2025.03.14) |
| May 1, 2025 | 16.09% (0.16085) | 94.44th | v4 (v2025.03.14) |
| Apr 14, 2025 | 31.14% (0.31142) | 96.39th | v4 (v2025.03.14) |
| Apr 13, 2025 | 16.09% (0.16085) | 94.25th | v4 (v2025.03.14) |
| Mar 29, 2025 | 31.19% (0.31191) | 94.90th | v4 (v2025.03.14) |
| Mar 28, 2025 | 16.09% (0.16085) | 94.24th | v4 (v2025.03.14) |
| Mar 17, 2025 | 31.14% (0.31142) | 96.36th | v4 (v2025.03.14) |
| Dec 12, 2024 | 0.16% (0.00164) | 54.39th | v3 (v2023.03.01) |
| Jun 26, 2024 | 0.16% (0.00164) | 53.26th | v3 (v2023.03.01) |
| Mar 7, 2023 | 0.16% (0.00164) | 51.25th | v3 (v2023.03.01) |
| Mar 6, 2023 | 2.36% (0.02359) | 81.45th | v2 (v2022.01.01) |
| Apr 1, 2022 | 2.36% (0.02359) | 79.69th | v2 (v2022.01.01) |
| Feb 4, 2022 | 2.36% (0.02359) | 58.33th | v2 (v2022.01.01) |
References (7)
- http://mailman.nginx.org/pipermail/nginx-announce/2014/000144.html mailing-listx_refsource_MLISTPatchVendor Advisory
- http://marc.info/?l=bugtraq&m=142103967620673&w=2 vendor-advisoryx_refsource_HPIssue TrackingThird Party Advisory
- http://nginx.org/download/patch.2014.starttls.txt x_refsource_CONFIRMPatchVendor Advisory
- https://access.redhat.com/security/cve/CVE-2014-3556 Vendor Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=1126891 x_refsource_CONFIRMIssue TrackingThird Party Advisory
- https://nvd.nist.gov/vuln/detail/CVE-2014-3556
- https://www.cve.org/CVERecord?id=CVE-2014-3556
| Link | Providers | Tags |
|---|---|---|
| http://mailman.nginx.org/pipermail/nginx-announce/2014/000144.html | mailing-listx_refsource_MLISTPatchVendor Advisory | |
| http://marc.info/?l=bugtraq&m=142103967620673&w=2 | vendor-advisoryx_refsource_HPIssue TrackingThird Party Advisory | |
| http://nginx.org/download/patch.2014.starttls.txt | x_refsource_CONFIRMPatchVendor Advisory | |
| https://access.redhat.com/security/cve/CVE-2014-3556 | Vendor Advisory | |
| https://bugzilla.redhat.com/show_bug.cgi?id=1126891 | x_refsource_CONFIRMIssue TrackingThird Party Advisory | |
| https://nvd.nist.gov/vuln/detail/CVE-2014-3556 | ||
| https://www.cve.org/CVERecord?id=CVE-2014-3556 |
Change history (0)
No recorded changes yet.