CVE-2023-51764 (GCVE-0-2023-51764)

Vulnerability from cvelistv5 – Published: 2023-12-24 00:00 – Updated: 2025-11-04 22:05
VLAI
Summary
Postfix through 3.8.5 allows SMTP smuggling unless configured with smtpd_data_restrictions=reject_unauth_pipelining and smtpd_discard_ehlo_keywords=chunking (or certain other options that exist in recent versions). 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 Postfix supports <LF>.<CR><LF> but some other popular e-mail servers do not. To prevent attack variants (by always disallowing <LF> without <CR>), a different solution is required, such as the smtpd_forbid_bare_newline=yes option with a Postfix minimum version of 3.5.23, 3.6.13, 3.7.9, 3.8.4, or 3.9.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CWE
  • n/a
Assigner
References
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2025-11-04T22:05:26.900Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://www.postfix.org/smtp-smuggling.html"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/"
          },
          {
            "name": "[oss-security] 20231224 Re: Re: New SMTP smuggling attack",
            "tags": [
              "mailing-list",
              "x_transferred"
            ],
            "url": "http://www.openwall.com/lists/oss-security/2023/12/24/1"
          },
          {
            "name": "[oss-security] 20231225 Re: Re: New SMTP smuggling attack",
            "tags": [
              "mailing-list",
              "x_transferred"
            ],
            "url": "http://www.openwall.com/lists/oss-security/2023/12/25/1"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2255563"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://access.redhat.com/security/cve/CVE-2023-51764"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://github.com/eeenvik1/CVE-2023-51764"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://github.com/duy-31/CVE-2023-51764"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://www.youtube.com/watch?v=V8KPV96g1To"
          },
          {
            "name": "FEDORA-2024-c839e7294f",
            "tags": [
              "vendor-advisory",
              "x_transferred"
            ],
            "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QRLF5SOS7TP5N7FQSEK2NFNB44ISVTZC/"
          },
          {
            "name": "FEDORA-2024-5c186175f2",
            "tags": [
              "vendor-advisory",
              "x_transferred"
            ],
            "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JQ5WXFCW2N6G2PH3JXDTYW5PH5EBQEGO/"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://lwn.net/Articles/956533/"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://www.openwall.com/lists/oss-security/2024/01/22/1"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://www.postfix.org/announcements/postfix-3.8.5.html"
          },
          {
            "name": "[debian-lts-announce] 20240130 [SECURITY] [DLA 3725-1] postfix security update",
            "tags": [
              "mailing-list",
              "x_transferred"
            ],
            "url": "https://lists.debian.org/debian-lts-announce/2024/01/msg00020.html"
          },
          {
            "name": "[oss-security] 20240508 Re: New SMTP smuggling attack",
            "tags": [
              "mailing-list",
              "x_transferred"
            ],
            "url": "http://www.openwall.com/lists/oss-security/2024/05/09/3"
          },
          {
            "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QRLF5SOS7TP5N7FQSEK2NFNB44ISVTZC/"
          },
          {
            "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/JQ5WXFCW2N6G2PH3JXDTYW5PH5EBQEGO/"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "n/a",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Postfix through 3.8.5 allows SMTP smuggling unless configured with smtpd_data_restrictions=reject_unauth_pipelining and smtpd_discard_ehlo_keywords=chunking (or certain other options that exist in recent versions). 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 Postfix supports \u003cLF\u003e.\u003cCR\u003e\u003cLF\u003e but some other popular e-mail servers do not. To prevent attack variants (by always disallowing \u003cLF\u003e without \u003cCR\u003e), a different solution is required, such as the smtpd_forbid_bare_newline=yes option with a Postfix minimum version of 3.5.23, 3.6.13, 3.7.9, 3.8.4, or 3.9."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "n/a",
              "lang": "en",
              "type": "text"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2024-06-10T18:07:59.991Z",
        "orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
        "shortName": "mitre"
      },
      "references": [
        {
          "url": "https://www.postfix.org/smtp-smuggling.html"
        },
        {
          "url": "https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/"
        },
        {
          "name": "[oss-security] 20231224 Re: Re: New SMTP smuggling attack",
          "tags": [
            "mailing-list"
          ],
          "url": "http://www.openwall.com/lists/oss-security/2023/12/24/1"
        },
        {
          "name": "[oss-security] 20231225 Re: Re: New SMTP smuggling attack",
          "tags": [
            "mailing-list"
          ],
          "url": "http://www.openwall.com/lists/oss-security/2023/12/25/1"
        },
        {
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2255563"
        },
        {
          "url": "https://access.redhat.com/security/cve/CVE-2023-51764"
        },
        {
          "url": "https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html"
        },
        {
          "url": "https://github.com/eeenvik1/CVE-2023-51764"
        },
        {
          "url": "https://github.com/duy-31/CVE-2023-51764"
        },
        {
          "url": "https://www.youtube.com/watch?v=V8KPV96g1To"
        },
        {
          "name": "FEDORA-2024-c839e7294f",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QRLF5SOS7TP5N7FQSEK2NFNB44ISVTZC/"
        },
        {
          "name": "FEDORA-2024-5c186175f2",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JQ5WXFCW2N6G2PH3JXDTYW5PH5EBQEGO/"
        },
        {
          "url": "https://lwn.net/Articles/956533/"
        },
        {
          "url": "https://www.openwall.com/lists/oss-security/2024/01/22/1"
        },
        {
          "url": "https://www.postfix.org/announcements/postfix-3.8.5.html"
        },
        {
          "name": "[debian-lts-announce] 20240130 [SECURITY] [DLA 3725-1] postfix security update",
          "tags": [
            "mailing-list"
          ],
          "url": "https://lists.debian.org/debian-lts-announce/2024/01/msg00020.html"
        },
        {
          "name": "[oss-security] 20240508 Re: New SMTP smuggling attack",
          "tags": [
            "mailing-list"
          ],
          "url": "http://www.openwall.com/lists/oss-security/2024/05/09/3"
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
    "assignerShortName": "mitre",
    "cveId": "CVE-2023-51764",
    "datePublished": "2023-12-24T00:00:00.000Z",
    "dateReserved": "2023-12-24T00:00:00.000Z",
    "dateUpdated": "2025-11-04T22:05:26.900Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2023-51764",
      "date": "2026-06-04",
      "epss": "0.2846",
      "percentile": "0.96609"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2023-51764\",\"sourceIdentifier\":\"cve@mitre.org\",\"published\":\"2023-12-24T05:15:08.273\",\"lastModified\":\"2025-11-04T22:15:56.210\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Postfix through 3.8.5 allows SMTP smuggling unless configured with smtpd_data_restrictions=reject_unauth_pipelining and smtpd_discard_ehlo_keywords=chunking (or certain other options that exist in recent versions). 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 Postfix supports \u003cLF\u003e.\u003cCR\u003e\u003cLF\u003e but some other popular e-mail servers do not. To prevent attack variants (by always disallowing \u003cLF\u003e without \u003cCR\u003e), a different solution is required, such as the smtpd_forbid_bare_newline=yes option with a Postfix minimum version of 3.5.23, 3.6.13, 3.7.9, 3.8.4, or 3.9.\"},{\"lang\":\"es\",\"value\":\"Postfix hasta 3.8.4 permite el contrabando SMTP a menos que se configure con smtpd_data_restrictions=reject_unauth_pipelining (u otras opciones que existen en versiones recientes). Los atacantes remotos pueden utilizar una t\u00e9cnica de explotaci\u00f3n publicada para inyectar mensajes de correo electr\u00f3nico que parecen originarse en el servidor Postfix, lo que permite omitir un mecanismo de protecci\u00f3n SPF. Esto ocurre porque Postfix admite . pero algunos otros servidores de correo electr\u00f3nico populares no lo hacen. Para evitar variantes de ataque (al no permitir siempre  sin ), se requiere una soluci\u00f3n diferente: la opci\u00f3n smtpd_forbid_bare_newline=yes con una versi\u00f3n m\u00ednima de Postfix de 3.5.23, 3.6.13, 3.7.9, 3.8.4, o 3.9.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N\",\"baseScore\":5.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":3.9,\"impactScore\":1.4}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-345\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:postfix:postfix:*:*:*:*:*:*:*:*\",\"versionEndExcluding\":\"3.5.23\",\"matchCriteriaId\":\"0598FFA3-9DB8-4D01-9049-3834B6B53000\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:postfix:postfix:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"3.6.0\",\"versionEndExcluding\":\"3.6.13\",\"matchCriteriaId\":\"7AD4364D-F93C-499E-8ECA-5228354D20B6\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:postfix:postfix:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"3.7.0\",\"versionEndExcluding\":\"3.7.9\",\"matchCriteriaId\":\"7174307B-1249-47B5-BE66-9194AC26BA15\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:postfix:postfix:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"3.8.0\",\"versionEndExcluding\":\"3.8.4\",\"matchCriteriaId\":\"7A422C34-3E0E-4C3F-8EA9-4F442D88057D\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:fedoraproject:fedora:38:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"CC559B26-5DFC-4B7A-A27C-B77DE755DFF9\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:fedoraproject:fedora:39:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"B8EDB836-4E6A-4B71-B9B2-AA3E03E0F646\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"F4CFF558-3C47-480D-A2F0-BABF26042943\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"7F6FB57C-2BC7-487C-96DD-132683AEB35D\"}]}]}],\"references\":[{\"url\":\"http://www.openwall.com/lists/oss-security/2023/12/24/1\",\"source\":\"cve@mitre.org\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]},{\"url\":\"http://www.openwall.com/lists/oss-security/2023/12/25/1\",\"source\":\"cve@mitre.org\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]},{\"url\":\"http://www.openwall.com/lists/oss-security/2024/05/09/3\",\"source\":\"cve@mitre.org\"},{\"url\":\"https://access.redhat.com/security/cve/CVE-2023-51764\",\"source\":\"cve@mitre.org\",\"tags\":[\"Third Party Advisory\"]},{\"url\":\"https://bugzilla.redhat.com/show_bug.cgi?id=2255563\",\"source\":\"cve@mitre.org\",\"tags\":[\"Issue Tracking\",\"Third Party Advisory\"]},{\"url\":\"https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html\",\"source\":\"cve@mitre.org\",\"tags\":[\"Technical Description\"]},{\"url\":\"https://github.com/duy-31/CVE-2023-51764\",\"source\":\"cve@mitre.org\",\"tags\":[\"Exploit\",\"Third Party Advisory\"]},{\"url\":\"https://github.com/eeenvik1/CVE-2023-51764\",\"source\":\"cve@mitre.org\",\"tags\":[\"Exploit\",\"Third Party Advisory\"]},{\"url\":\"https://lists.debian.org/debian-lts-announce/2024/01/msg00020.html\",\"source\":\"cve@mitre.org\"},{\"url\":\"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JQ5WXFCW2N6G2PH3JXDTYW5PH5EBQEGO/\",\"source\":\"cve@mitre.org\"},{\"url\":\"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QRLF5SOS7TP5N7FQSEK2NFNB44ISVTZC/\",\"source\":\"cve@mitre.org\"},{\"url\":\"https://lwn.net/Articles/956533/\",\"source\":\"cve@mitre.org\"},{\"url\":\"https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/\",\"source\":\"cve@mitre.org\",\"tags\":[\"Technical Description\",\"Third Party Advisory\"]},{\"url\":\"https://www.openwall.com/lists/oss-security/2024/01/22/1\",\"source\":\"cve@mitre.org\"},{\"url\":\"https://www.postfix.org/announcements/postfix-3.8.5.html\",\"source\":\"cve@mitre.org\"},{\"url\":\"https://www.postfix.org/smtp-smuggling.html\",\"source\":\"cve@mitre.org\",\"tags\":[\"Exploit\",\"Mitigation\",\"Vendor Advisory\"]},{\"url\":\"https://www.youtube.com/watch?v=V8KPV96g1To\",\"source\":\"cve@mitre.org\",\"tags\":[\"Exploit\"]},{\"url\":\"http://www.openwall.com/lists/oss-security/2023/12/24/1\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]},{\"url\":\"http://www.openwall.com/lists/oss-security/2023/12/25/1\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Mailing List\",\"Third Party Advisory\"]},{\"url\":\"http://www.openwall.com/lists/oss-security/2024/05/09/3\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://access.redhat.com/security/cve/CVE-2023-51764\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Third Party Advisory\"]},{\"url\":\"https://bugzilla.redhat.com/show_bug.cgi?id=2255563\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Issue Tracking\",\"Third Party Advisory\"]},{\"url\":\"https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Technical Description\"]},{\"url\":\"https://github.com/duy-31/CVE-2023-51764\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Exploit\",\"Third Party Advisory\"]},{\"url\":\"https://github.com/eeenvik1/CVE-2023-51764\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Exploit\",\"Third Party Advisory\"]},{\"url\":\"https://lists.debian.org/debian-lts-announce/2024/01/msg00020.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JQ5WXFCW2N6G2PH3JXDTYW5PH5EBQEGO/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QRLF5SOS7TP5N7FQSEK2NFNB44ISVTZC/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/JQ5WXFCW2N6G2PH3JXDTYW5PH5EBQEGO/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QRLF5SOS7TP5N7FQSEK2NFNB44ISVTZC/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://lwn.net/Articles/956533/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Technical Description\",\"Third Party Advisory\"]},{\"url\":\"https://www.openwall.com/lists/oss-security/2024/01/22/1\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://www.postfix.org/announcements/postfix-3.8.5.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://www.postfix.org/smtp-smuggling.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Exploit\",\"Mitigation\",\"Vendor Advisory\"]},{\"url\":\"https://www.youtube.com/watch?v=V8KPV96g1To\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Exploit\"]}]}}"
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.