zeromq3 — security advisory
In ZeroMQ before version 4.3.3, there is a denial-of-service vulnerability. Users with TCP transport public endpoints, even with CURVE/ZAP enabled, are impacted. If a raw TCP socket is opened and connected to an endpoint that is fully configured with CURVE/ZAP, legitimate clients will not be able to exchange any message. Handshakes complete successfully, and messages are delivered to the library, but the server application never receives them. This is patched in version 4.3.3.
- Products
- zeromq3
- Affected versions
- Not specified
- Fixed versions
- 4.3.3-1
- CVEs
- CVE-2020-15166
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 13:26 UTC · Revision 1
Source evidence
In ZeroMQ before version 4.3.3, there is a denial-of-service vulnerability. Users with TCP transport public endpoints, even with CURVE/ZAP enabled, are impacted. If a raw TCP socket is opened and connected to an endpoint that is fully configured with CURVE/ZAP, legitimate clients will not be able to exchange any message. Handshakes complete successfully, and messages are delivered to the library, but the server application never receives them. This is patched in version 4.3.3.
osv:DEBIAN-CVE-2020-15166
zeromq3
Fixed versions: 4.3.3-1
zeromq3
Fixed versions: 4.3.3-1
zeromq3
Fixed versions: 4.3.3-1
Complete source record
{
"id": "35e1deb2fe4fe4c480afdf86032aa65120010767d805fc57fa550d786947f503",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2020-15166",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2020-15166",
"summary": "In ZeroMQ before version 4.3.3, there is a denial-of-service vulnerability. Users with TCP transport public endpoints, even with CURVE/ZAP enabled, are impacted. If a raw TCP socket is opened and connected to an endpoint that is fully configured with CURVE/ZAP, legitimate clients will not be able to exchange any message. Handshakes complete successfully, and messages are delivered to the library, but the server application never receives them. This is patched in version 4.3.3.",
"evidence": "osv:DEBIAN-CVE-2020-15166",
"products": [
{
"name": {
"value": "zeromq3",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.3.3-1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "zeromq3",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.3.3-1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "zeromq3",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "4.3.3-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
}
],
"severity": "high",
"structured": {
"id": "DEBIAN-CVE-2020-15166",
"aliases": [
"DEBIAN-CVE-2020-15166"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.3.3-1"
}
]
}
],
"package": {
"name": "zeromq3",
"purl": "pkg:deb/debian/zeromq3?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-15166.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.3.3-1"
}
]
}
],
"package": {
"name": "zeromq3",
"purl": "pkg:deb/debian/zeromq3?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-15166.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "4.3.3-1"
}
]
}
],
"package": {
"name": "zeromq3",
"purl": "pkg:deb/debian/zeromq3?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-15166.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-26T12:02:27.178853846Z",
"provider": "osv",
"upstream": [
"CVE-2020-15166"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2020-15166"
]
},
"related_cves": [
{
"value": "CVE-2020-15166",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 452233,
"published_at": "2020-09-11T16:15:12.177+00:00"
}