High
courier — security advisory
An issue was discovered in the POP3 component of Courier Mail Server before 1.1.5. Meddler-in-the-middle attackers can pipeline commands after the POP3 STLS command, injecting plaintext commands into an encrypted user session.
- Products
- courier
- Affected versions
- 0.68.2-1ubuntu5, 0.68.2-1ubuntu6, 0.68.2-1ubuntu7, 0.78.0-2, 0.78.0-2ubuntu1, 0.78.0-2ubuntu2, 1.0.16-3build1, 1.0.16-3build2, 1.0.16-3build3, 1.0.6-1build1, 1.0.6-1build2, 1.3.13-11, 1.4.1-1, 1.4.1-10, 1.4.1-2, 1.4.1-2build1, 1.4.1-3, 1.5.1-2, 1.5.1-4, 2.0.6-1
- Fixed versions
- Not specified
- CVEs
- CVE-2021-38084
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 01:37 UTC · Revision 1
Source evidence
An issue was discovered in the POP3 component of Courier Mail Server before 1.1.5. Meddler-in-the-middle attackers can pipeline commands after the POP3 STLS command, injecting plaintext commands into an encrypted user session.
osv:UBUNTU-CVE-2021-38084
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
courier
Fixed versions: Not specified
Complete source record
{
"id": "cb41bb720d7dbe2942daed527a7d9082bd7138d48d64f2335063fbf44263d748",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2021-38084",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2021-38084",
"summary": "An issue was discovered in the POP3 component of Courier Mail Server before 1.1.5. Meddler-in-the-middle attackers can pipeline commands after the POP3 STLS command, injecting plaintext commands into an encrypted user session.",
"evidence": "osv:UBUNTU-CVE-2021-38084",
"products": [
{
"name": {
"value": "courier",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.68.2-1ubuntu5",
"evidence": "/affected/0/versions"
},
{
"value": "0.68.2-1ubuntu6",
"evidence": "/affected/0/versions"
},
{
"value": "0.68.2-1ubuntu7",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "0.78.0-2",
"evidence": "/affected/1/versions"
},
{
"value": "0.78.0-2ubuntu1",
"evidence": "/affected/1/versions"
},
{
"value": "0.78.0-2ubuntu2",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.0.6-1build1",
"evidence": "/affected/2/versions"
},
{
"value": "1.0.6-1build2",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.0.16-3build1",
"evidence": "/affected/3/versions"
},
{
"value": "1.0.16-3build2",
"evidence": "/affected/3/versions"
},
{
"value": "1.0.16-3build3",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.3.13-11",
"evidence": "/affected/4/versions"
},
{
"value": "1.4.1-1",
"evidence": "/affected/4/versions"
},
{
"value": "1.4.1-2",
"evidence": "/affected/4/versions"
},
{
"value": "1.4.1-2build1",
"evidence": "/affected/4/versions"
},
{
"value": "1.4.1-3",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.5.1-2",
"evidence": "/affected/5/versions"
},
{
"value": "1.5.1-4",
"evidence": "/affected/5/versions"
},
{
"value": "2.0.6-1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "courier",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.4.1-3",
"evidence": "/affected/6/versions"
},
{
"value": "1.4.1-10",
"evidence": "/affected/6/versions"
},
{
"value": "1.5.1-2",
"evidence": "/affected/6/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2021-38084",
"aliases": [
"UBUNTU-CVE-2021-38084"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"0.68.2-1ubuntu5",
"0.68.2-1ubuntu6",
"0.68.2-1ubuntu7"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-38084.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-faxmail",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-imap",
"binary_version": "4.10.0-20120615-1ubuntu7"
},
{
"binary_name": "courier-imap-ssl",
"binary_version": "4.10.0-20120615-1ubuntu7"
},
{
"binary_name": "courier-ldap",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-maildrop",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-mlm",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-mta",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-mta-ssl",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-pcp",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-pop",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-pop-ssl",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-ssl",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "courier-webadmin",
"binary_version": "0.68.2-1ubuntu7"
},
{
"binary_name": "sqwebmail",
"binary_version": "0.68.2-1ubuntu7"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
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}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=bionic",
"ecosystem": "Ubuntu:18.04:LTS"
},
"versions": [
"0.78.0-2",
"0.78.0-2ubuntu1",
"0.78.0-2ubuntu2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-38084.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-faxmail",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-imap",
"binary_version": "4.18.1+0.78.0-2ubuntu2"
},
{
"binary_name": "courier-imap-ssl",
"binary_version": "4.18.1+0.78.0-2ubuntu2"
},
{
"binary_name": "courier-ldap",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-maildrop",
"binary_version": "2.9.1+0.78.0-2ubuntu2"
},
{
"binary_name": "courier-mlm",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-mta",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-mta-ssl",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-pcp",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-pop",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-pop-ssl",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-ssl",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "courier-webadmin",
"binary_version": "0.78.0-2ubuntu2"
},
{
"binary_name": "sqwebmail",
"binary_version": "5.9.0+0.78.0-2ubuntu2"
}
]
}
},
{
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"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=focal",
"ecosystem": "Ubuntu:20.04:LTS"
},
"versions": [
"1.0.6-1build1",
"1.0.6-1build2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-38084.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-faxmail",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-imap",
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{
"binary_name": "courier-ldap",
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{
"binary_name": "courier-mlm",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-mta",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-pcp",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-pop",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "courier-webadmin",
"binary_version": "1.0.6-1build2"
},
{
"binary_name": "sqwebmail",
"binary_version": "6.0.0+1.0.6-1build2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"1.0.16-3build1",
"1.0.16-3build2",
"1.0.16-3build3"
],
"database_specific": {
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},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-faxmail",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-imap",
"binary_version": "5.0.13+1.0.16-3build3"
},
{
"binary_name": "courier-ldap",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-mlm",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-mta",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-pcp",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-pop",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "courier-webadmin",
"binary_version": "1.0.16-3build3"
},
{
"binary_name": "sqwebmail",
"binary_version": "6.0.5+1.0.16-3build3"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"1.3.13-11",
"1.4.1-1",
"1.4.1-2",
"1.4.1-2build1",
"1.4.1-3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-38084.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "1.4.1-3"
},
{
"binary_name": "courier-faxmail",
"binary_version": "1.4.1-3"
},
{
"binary_name": "courier-imap",
"binary_version": "5.2.11+1.4.1-3"
},
{
"binary_name": "courier-ldap",
"binary_version": "1.4.1-3"
},
{
"binary_name": "courier-mlm",
"binary_version": "1.4.1-3"
},
{
"binary_name": "courier-mta",
"binary_version": "1.4.1-3"
},
{
"binary_name": "courier-pcp",
"binary_version": "1.4.1-3"
},
{
"binary_name": "courier-pop",
"binary_version": "1.4.1-3"
},
{
"binary_name": "courier-webadmin",
"binary_version": "1.4.1-3"
},
{
"binary_name": "sqwebmail",
"binary_version": "6.2.9+1.4.1-3"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"1.5.1-2",
"1.5.1-4",
"2.0.6-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-38084.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-faxmail",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-imap",
"binary_version": "6.0.5+2.0.6-1"
},
{
"binary_name": "courier-ldap",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-mlm",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-mta",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-pcp",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-pop",
"binary_version": "2.0.6-1"
},
{
"binary_name": "courier-webadmin",
"binary_version": "2.0.6-1"
},
{
"binary_name": "sqwebmail",
"binary_version": "7.0.4+2.0.6-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "courier",
"purl": "pkg:deb/ubuntu/courier?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.4.1-3",
"1.4.1-10",
"1.5.1-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-38084.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "courier-base",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-faxmail",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-imap",
"binary_version": "5.3.1+1.5.1-2"
},
{
"binary_name": "courier-ldap",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-mlm",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-mta",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-pcp",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-pop",
"binary_version": "1.5.1-2"
},
{
"binary_name": "courier-webadmin",
"binary_version": "1.5.1-2"
},
{
"binary_name": "sqwebmail",
"binary_version": "6.3.1+1.5.1-2"
}
]
}
}
],
"modified": "2026-10-17T12:57:14.080643001Z",
"provider": "osv",
"upstream": [
"CVE-2021-38084"
],
"references": [
"https://ubuntu.com/security/CVE-2021-38084",
"https://sourceforge.net/p/courier/mailman/courier-imap/thread/cone.1382574216.483027.8082.1000%40monster.email-scan.com/#msg31555583",
"https://sourceforge.net/p/courier/mailman/message/37329216/",
"https://www.cve.org/CVERecord?id=CVE-2021-38084"
]
},
"related_cves": [
{
"value": "CVE-2021-38084",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 356977,
"published_at": "2021-08-03T22:15:00+00:00"
}