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SMTP smuggling in aiosmtpd

Type: advisorySources: OSV

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

SMTP smuggling in aiosmtpd

core-osv · Original source

Published 12 Mar 2024, 20:29 UTC

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"
}