HighFix available
libetpan — security advisory
LibEtPan through 1.9.4, as used in MailCore 2 through 0.6.3 and other products, has a STARTTLS buffering issue that affects IMAP, SMTP, and POP3. When a server sends a "begin TLS" response, the client reads additional data (e.g., from a meddler-in-the-middle attacker) and evaluates it in a TLS context, aka "response injection."
- Products
- libetpan
- Affected versions
- 1.10.0-1, 1.10.0-1.1, 1.5-2, 1.6-1, 1.6-1build1, 1.8.0-1, 1.8.0-1ubuntu0.1~esm1, 1.9.3-2, 1.9.4-2, 1.9.4-2ubuntu0.1~esm1, 1.9.4-3, 1.9.4-3+deb11u1build0.22.04.1, 1.9.4-3.1, 1.9.4-3.2, 1.9.4-3.2build1, 1.9.4-3.2build2, 1.9.4-5, 1.9.4-6, 1.9.4-7, 1.9.4-8
- Fixed versions
- 1.6-1ubuntu0.1
- CVEs
- CVE-2020-15953
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 00:51 UTC · Revision 1
Source evidence
LibEtPan through 1.9.4, as used in MailCore 2 through 0.6.3 and other products, has a STARTTLS buffering issue that affects IMAP, SMTP, and POP3. When a server sends a "begin TLS" response, the client reads additional data (e.g., from a meddler-in-the-middle attacker) and evaluates it in a TLS context, aka "response injection."
osv:UBUNTU-CVE-2020-15953
libetpan
Fixed versions: 1.6-1ubuntu0.1
libetpan
Fixed versions: Not specified
libetpan
Fixed versions: Not specified
libetpan
Fixed versions: Not specified
libetpan
Fixed versions: Not specified
libetpan
Fixed versions: Not specified
libetpan
Fixed versions: Not specified
libetpan
Fixed versions: Not specified
Complete source record
{
"id": "3059a1947a6dd75062e6e8bca1b18aeb11e393e4c182e05aaa862396ac706346",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2020-15953",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2020-15953",
"summary": "LibEtPan through 1.9.4, as used in MailCore 2 through 0.6.3 and other products, has a STARTTLS buffering issue that affects IMAP, SMTP, and POP3. When a server sends a \"begin TLS\" response, the client reads additional data (e.g., from a meddler-in-the-middle attacker) and evaluates it in a TLS context, aka \"response injection.\"",
"evidence": "osv:UBUNTU-CVE-2020-15953",
"products": [
{
"name": {
"value": "libetpan",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "1.6-1ubuntu0.1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "1.5-2",
"evidence": "/affected/0/versions"
},
{
"value": "1.6-1",
"evidence": "/affected/0/versions"
},
{
"value": "1.6-1build1",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "libetpan",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.8.0-1",
"evidence": "/affected/1/versions"
},
{
"value": "1.8.0-1ubuntu0.1~esm1",
"evidence": "/affected/1/versions"
}
]
},
{
"name": {
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"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.9.3-2",
"evidence": "/affected/2/versions"
},
{
"value": "1.9.4-2",
"evidence": "/affected/2/versions"
},
{
"value": "1.9.4-2ubuntu0.1~esm1",
"evidence": "/affected/2/versions"
}
]
},
{
"name": {
"value": "libetpan",
"evidence": "/affected/3/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.9.4-3",
"evidence": "/affected/3/versions"
},
{
"value": "1.9.4-3+deb11u1build0.22.04.1",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "libetpan",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.9.4-3.1",
"evidence": "/affected/4/versions"
},
{
"value": "1.9.4-3.2",
"evidence": "/affected/4/versions"
},
{
"value": "1.9.4-3.2build1",
"evidence": "/affected/4/versions"
},
{
"value": "1.9.4-3.2build2",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "libetpan",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.9.4-5",
"evidence": "/affected/5/versions"
},
{
"value": "1.9.4-6",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "libetpan",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.9.4-8",
"evidence": "/affected/6/versions"
},
{
"value": "1.10.0-1",
"evidence": "/affected/6/versions"
},
{
"value": "1.10.0-1.1",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "libetpan",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "1.9.4-6",
"evidence": "/affected/7/versions"
},
{
"value": "1.9.4-7",
"evidence": "/affected/7/versions"
},
{
"value": "1.9.4-8",
"evidence": "/affected/7/versions"
}
]
}
],
"severity": "high",
"structured": {
"id": "UBUNTU-CVE-2020-15953",
"aliases": [
"UBUNTU-CVE-2020-15953"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.6-1ubuntu0.1"
}
]
}
],
"package": {
"name": "libetpan",
"purl": "pkg:deb/ubuntu/libetpan?arch=source&distro=xenial",
"ecosystem": "Ubuntu:16.04:LTS"
},
"versions": [
"1.5-2",
"1.6-1",
"1.6-1build1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-15953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libetpan17",
"binary_version": "1.6-1ubuntu0.1"
}
],
"availability": "No subscription required"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libetpan",
"purl": "pkg:deb/ubuntu/libetpan?arch=source&distro=esm-apps%2Fbionic",
"ecosystem": "Ubuntu:Pro:18.04:LTS"
},
"versions": [
"1.8.0-1",
"1.8.0-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-15953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libetpan20",
"binary_version": "1.8.0-1ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libetpan",
"purl": "pkg:deb/ubuntu/libetpan?arch=source&distro=esm-apps%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
"versions": [
"1.9.3-2",
"1.9.4-2",
"1.9.4-2ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-15953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libetpan20",
"binary_version": "1.9.4-2ubuntu0.1~esm1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libetpan",
"purl": "pkg:deb/ubuntu/libetpan?arch=source&distro=jammy",
"ecosystem": "Ubuntu:22.04:LTS"
},
"versions": [
"1.9.4-3",
"1.9.4-3+deb11u1build0.22.04.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-15953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libetpan20",
"binary_version": "1.9.4-3+deb11u1build0.22.04.1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libetpan",
"purl": "pkg:deb/ubuntu/libetpan?arch=source&distro=noble",
"ecosystem": "Ubuntu:24.04:LTS"
},
"versions": [
"1.9.4-3.1",
"1.9.4-3.2",
"1.9.4-3.2build1",
"1.9.4-3.2build2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-15953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libetpan20t64",
"binary_version": "1.9.4-3.2build2"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libetpan",
"purl": "pkg:deb/ubuntu/libetpan?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"1.9.4-5",
"1.9.4-6"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-15953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libetpan20t64",
"binary_version": "1.9.4-6"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libetpan",
"purl": "pkg:deb/ubuntu/libetpan?arch=source&distro=stonking",
"ecosystem": "Ubuntu:26.10"
},
"versions": [
"1.9.4-8",
"1.10.0-1",
"1.10.0-1.1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-15953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libetpan20t64",
"binary_version": "1.10.0-1.1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
}
]
}
],
"package": {
"name": "libetpan",
"purl": "pkg:deb/ubuntu/libetpan?arch=source&distro=resolute",
"ecosystem": "Ubuntu:26.04:LTS"
},
"versions": [
"1.9.4-6",
"1.9.4-7",
"1.9.4-8"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2020/UBUNTU-CVE-2020-15953.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "libetpan20t64",
"binary_version": "1.9.4-8"
}
]
}
}
],
"modified": "2026-10-17T12:56:11.669294452Z",
"provider": "osv",
"upstream": [
"CVE-2020-15953"
],
"references": [
"https://ubuntu.com/security/CVE-2020-15953",
"https://security.gentoo.org/glsa/202007-55",
"https://ubuntu.com/security/notices/USN-4598-1",
"https://www.cve.org/CVERecord?id=CVE-2020-15953"
]
},
"related_cves": [
{
"value": "CVE-2020-15953",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 354938,
"published_at": "2020-07-27T07:15:00+00:00"
}