SMTP smuggling in aiosmtpd
aiosmtpd is a reimplementation of the Python stdlib smtpd.py based on asyncio. aiosmtpd is vulnerable to inbound SMTP smuggling. SMTP smuggling is a novel vulnerability based on not so novel interpretation differences of the SMTP protocol. By exploiting SMTP smuggling, an attacker may send smuggle/spoof e-mails with fake sender addresses, allowing advanced phishing attacks. This issue is also existed in other SMTP software like Postfix. With the right SMTP server constellation, an attacker can send spoofed e-mails to inbound/receiving aiosmtpd instances. This issue has been addressed in version 1.4.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.
- Products
- Not specified
- Affected versions
- Not specified
- Fixed versions
- Not specified
- CVEs
- CVE-2024-27305
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 4 Nov 2026, 13:45 UTC · Revision 1
Source evidence
aiosmtpd is a reimplementation of the Python stdlib smtpd.py based on asyncio. aiosmtpd is vulnerable to inbound SMTP smuggling. SMTP smuggling is a novel vulnerability based on not so novel interpretation differences of the SMTP protocol. By exploiting SMTP smuggling, an attacker may send smuggle/spoof e-mails with fake sender addresses, allowing advanced phishing attacks. This issue is also existed in other SMTP software like Postfix. With the right SMTP server constellation, an attacker can send spoofed e-mails to inbound/receiving aiosmtpd instances. This issue has been addressed in version 1.4.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.
osv:CVE-2024-27305
Complete source record
{
"id": "56473f870663d8a47464169421a1b306e2cb537069e3acdf22ca311b47c50ca1",
"url": "https://osv.dev/vulnerability/CVE-2024-27305",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "SMTP smuggling in aiosmtpd",
"summary": "aiosmtpd is a reimplementation of the Python stdlib smtpd.py based on asyncio. aiosmtpd is vulnerable to inbound SMTP smuggling. SMTP smuggling is a novel vulnerability based on not so novel interpretation differences of the SMTP protocol. By exploiting SMTP smuggling, an attacker may send smuggle/spoof e-mails with fake sender addresses, allowing advanced phishing attacks. This issue is also existed in other SMTP software like Postfix. With the right SMTP server constellation, an attacker can send spoofed e-mails to inbound/receiving aiosmtpd instances. This issue has been addressed in version 1.4.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.",
"evidence": "osv:CVE-2024-27305",
"products": [],
"severity": "medium",
"structured": {
"id": "CVE-2024-27305",
"aliases": [
"CVE-2024-27305",
"GHSA-pr2m-px7j-xg65",
"PYSEC-2024-221"
],
"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": [
{
"repo": "https://github.com/aio-libs/aiosmtpd",
"type": "GIT",
"events": [
{
"introduced": "0"
},
{
"fixed": "a99cfcf6e6f5fcc1c6f00b7fb653c4468c04bfb8"
},
{
"fixed": "24b6c79c8921cf1800e27ca144f4f37023982bbb"
}
],
"database_specific": {
"extracted_events": [
{
"cpe": "cpe:2.3:a:aio-libs:aiosmtpd:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "0"
},
{
"fixed": "1.4.5"
}
],
"source": "CPE_RANGE"
},
{
"range": [
{
"fixed": "24b6c79c8921cf1800e27ca144f4f37023982bbb"
}
],
"source": "REFERENCES_COMMIT"
}
]
}
}
],
"versions": [
"1.4.4.post2",
"1.4.4",
"1.4.3",
"1.4.3rc2",
"1.4.3rc1",
"1.4.2",
"1.4.1",
"1.4.0",
"1.3.2",
"1.3.1",
"1.3.0",
"1.3.0a3",
"1.3.0a2",
"1.2.4",
"1.2.3",
"1.2.2",
"1.2.1",
"1.2-rc",
"1.2",
"1.1",
"1.0",
"1.0rc1",
"1.0b1",
"1.0a5",
"1.0a4",
"1.0a3",
"1.0a2",
"1.0a1"
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2024-27305.json"
}
}
],
"modified": "2026-10-28T02:30:35.984419600Z",
"provider": "osv",
"references": [
"https://www.postfix.org/smtp-smuggling.html",
"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/27xxx/CVE-2024-27305.json",
"https://github.com/aio-libs/aiosmtpd/security/advisories/GHSA-pr2m-px7j-xg65",
"https://nvd.nist.gov/vuln/detail/CVE-2024-27305",
"https://github.com/aio-libs/aiosmtpd/commit/24b6c79c8921cf1800e27ca144f4f37023982bbb"
],
"provider_metadata": {
"cwe_ids": [
"CWE-345"
],
"cna_assigner": "GitHub_M",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/27xxx/CVE-2024-27305.json"
}
},
"related_cves": [
{
"value": "CVE-2024-27305",
"evidence": "/id"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 503238,
"published_at": "2024-03-12T20:29:54.592+00:00"
}