sendmail — security advisory
sendmail through 8.17.2 allows SMTP smuggling in certain configurations. Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because sendmail supports . but some other popular e-mail servers do not. This is resolved in 8.18 and later versions with 'o' in srv_features.
- Products
- sendmail
- Affected versions
- 8.17.1.9-2
- Fixed versions
- 8.17.1.9-2+deb12u1, 8.18.1-1
- CVEs
- CVE-2023-51765
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 1 Nov 2026, 15:49 UTC · Revision 1
Source evidence
sendmail through 8.17.2 allows SMTP smuggling in certain configurations. Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because sendmail supports . but some other popular e-mail servers do not. This is resolved in 8.18 and later versions with 'o' in srv_features.
osv:DEBIAN-CVE-2023-51765
sendmail
Fixed versions: 8.17.1.9-2+deb12u1
sendmail
Fixed versions: 8.18.1-1
sendmail
Fixed versions: 8.18.1-1
Complete source record
{
"id": "e4ca85dfd6aafd3a377f17ca31164e60468be95ab80fc8c9888921a87611b066",
"url": "https://osv.dev/vulnerability/DEBIAN-CVE-2023-51765",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "DEBIAN-CVE-2023-51765",
"summary": "sendmail through 8.17.2 allows SMTP smuggling in certain configurations. Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because sendmail supports . but some other popular e-mail servers do not. This is resolved in 8.18 and later versions with 'o' in srv_features.",
"evidence": "osv:DEBIAN-CVE-2023-51765",
"products": [
{
"name": {
"value": "sendmail",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "8.17.1.9-2+deb12u1",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "8.17.1.9-2",
"evidence": "/affected/0/versions"
}
]
},
{
"name": {
"value": "sendmail",
"evidence": "/affected/1/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "8.18.1-1",
"evidence": "/affected/1/ranges"
}
],
"affected_versions": []
},
{
"name": {
"value": "sendmail",
"evidence": "/affected/2/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "8.18.1-1",
"evidence": "/affected/2/ranges"
}
],
"affected_versions": []
}
],
"severity": "medium",
"structured": {
"id": "DEBIAN-CVE-2023-51765",
"aliases": [
"DEBIAN-CVE-2023-51765"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "8.17.1.9-2+deb12u1"
}
]
}
],
"package": {
"name": "sendmail",
"purl": "pkg:deb/debian/sendmail?arch=source&distro=bookworm",
"ecosystem": "Debian:12"
},
"versions": [
"8.17.1.9-2"
],
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-51765.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "8.18.1-1"
}
]
}
],
"package": {
"name": "sendmail",
"purl": "pkg:deb/debian/sendmail?arch=source&distro=trixie",
"ecosystem": "Debian:13"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-51765.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "8.18.1-1"
}
]
}
],
"package": {
"name": "sendmail",
"purl": "pkg:deb/debian/sendmail?arch=source&distro=forky",
"ecosystem": "Debian:14"
},
"database_specific": {
"source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-51765.json"
},
"ecosystem_specific": {
"urgency": "not yet assigned"
}
}
],
"modified": "2026-10-26T18:01:56.628042421Z",
"provider": "osv",
"upstream": [
"CVE-2023-51765"
],
"references": [
"https://security-tracker.debian.org/tracker/CVE-2023-51765"
]
},
"related_cves": [
{
"value": "CVE-2023-51765",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 455771,
"published_at": "2023-12-24T06:15:07.527+00:00"
}