nginx — security advisory
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.
- Products
- nginx
- Affected versions
- Not specified
- Fixed versions
- 1.6.1-1
- CVEs
- CVE-2014-3556
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 21:49 UTC · Revision 1
Source evidence
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.
osv:DEBIAN-CVE-2014-3556
nginx
Fixed versions: 1.6.1-1
nginx
Fixed versions: 1.6.1-1
nginx
Fixed versions: 1.6.1-1
Complete source record
{
"id": "ea07e2da684f0223e19cf07100cb39096e700edc9e5b4b790bb58ee9cfe50166",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2014-3556",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2014-3556",
"summary": "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.",
"evidence": "osv:DEBIAN-CVE-2014-3556",
"products": [
{
"name": {
"value": "nginx",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.6.1-1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "nginx",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.6.1-1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "nginx",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.6.1-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
}
],
"severity": "unknown",
"structured": {
"id": "DEBIAN-CVE-2014-3556",
"aliases": [
"DEBIAN-CVE-2014-3556"
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.6.1-1"
}
]
}
],
"package": {
"name": "nginx",
"purl": "pkg:deb/debian/nginx?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2014-3556.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.6.1-1"
}
]
}
],
"package": {
"name": "nginx",
"purl": "pkg:deb/debian/nginx?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2014-3556.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.6.1-1"
}
]
}
],
"package": {
"name": "nginx",
"purl": "pkg:deb/debian/nginx?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2014-3556.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-23T15:47:39.684913537Z",
"provider": "osv",
"upstream": [
"CVE-2014-3556"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2014-3556"
]
},
"related_cves": [
{
"value": "CVE-2014-3556",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": null
},
"source_id": "core-osv",
"document_id": 414607,
"published_at": "2014-12-29T20:59:03.943+00:00"
}