CVE-2023-51766 (GCVE-0-2023-51766)
Vulnerability from cvelistv5
Published
2023-12-24 00:00
Modified
2025-11-04 18:21
Severity ?
CWE
  • n/a
Summary
Exim before 4.97.1 allows SMTP smuggling in certain PIPELINING/CHUNKING 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 Exim supports <LF>.<CR><LF> but some other popular e-mail servers do not.
References
Impacted products
Vendor Product Version
n/a n/a Version: n/a
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2025-11-04T18:21:35.998Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://exim.org/static/doc/security/CVE-2023-51766.txt"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://bugs.exim.org/show_bug.cgi?id=3063"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://www.openwall.com/lists/oss-security/2023/12/23/2"
          },
          {
            "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://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2255852"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html"
          },
          {
            "name": "[oss-security] 20231229 CVE-2023-51766: Exim: SMTP smuggling",
            "tags": [
              "mailing-list",
              "x_transferred"
            ],
            "url": "http://www.openwall.com/lists/oss-security/2023/12/29/2"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://github.com/Exim/exim/blob/master/doc/doc-txt/cve-2023-51766"
          },
          {
            "name": "[oss-security] 20240101 Re: CVE-2023-51766: Exim: SMTP smuggling",
            "tags": [
              "mailing-list",
              "x_transferred"
            ],
            "url": "http://www.openwall.com/lists/oss-security/2024/01/01/1"
          },
          {
            "name": "[oss-security] 20240101 Re: CVE-2023-51766: Exim: SMTP smuggling",
            "tags": [
              "mailing-list",
              "x_transferred"
            ],
            "url": "http://www.openwall.com/lists/oss-security/2024/01/01/2"
          },
          {
            "name": "[oss-security] 20240101 Re: CVE-2023-51766: Exim: SMTP smuggling",
            "tags": [
              "mailing-list",
              "x_transferred"
            ],
            "url": "http://www.openwall.com/lists/oss-security/2024/01/01/3"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://www.youtube.com/watch?v=V8KPV96g1To"
          },
          {
            "name": "[debian-lts-announce] 20240105 [SECURITY] [DLA 3708-1] exim4 security update",
            "tags": [
              "mailing-list",
              "x_transferred"
            ],
            "url": "https://lists.debian.org/debian-lts-announce/2024/01/msg00002.html"
          },
          {
            "name": "FEDORA-2024-1ef6197a49",
            "tags": [
              "vendor-advisory",
              "x_transferred"
            ],
            "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/"
          },
          {
            "name": "FEDORA-2024-e0841c83bb",
            "tags": [
              "vendor-advisory",
              "x_transferred"
            ],
            "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://lwn.net/Articles/956533/"
          },
          {
            "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/"
          },
          {
            "url": "https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "n/a",
          "vendor": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Exim before 4.97.1 allows SMTP smuggling in certain PIPELINING/CHUNKING 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 Exim supports \u003cLF\u003e.\u003cCR\u003e\u003cLF\u003e but some other popular e-mail servers do not."
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "description": "n/a",
              "lang": "en",
              "type": "text"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2024-01-18T02:47:22.078Z",
        "orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
        "shortName": "mitre"
      },
      "references": [
        {
          "url": "https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/"
        },
        {
          "url": "https://exim.org/static/doc/security/CVE-2023-51766.txt"
        },
        {
          "url": "https://bugs.exim.org/show_bug.cgi?id=3063"
        },
        {
          "url": "https://www.openwall.com/lists/oss-security/2023/12/23/2"
        },
        {
          "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://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca"
        },
        {
          "url": "https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5"
        },
        {
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2255852"
        },
        {
          "url": "https://fahrplan.events.ccc.de/congress/2023/fahrplan/events/11782.html"
        },
        {
          "name": "[oss-security] 20231229 CVE-2023-51766: Exim: SMTP smuggling",
          "tags": [
            "mailing-list"
          ],
          "url": "http://www.openwall.com/lists/oss-security/2023/12/29/2"
        },
        {
          "url": "https://github.com/Exim/exim/blob/master/doc/doc-txt/cve-2023-51766"
        },
        {
          "name": "[oss-security] 20240101 Re: CVE-2023-51766: Exim: SMTP smuggling",
          "tags": [
            "mailing-list"
          ],
          "url": "http://www.openwall.com/lists/oss-security/2024/01/01/1"
        },
        {
          "name": "[oss-security] 20240101 Re: CVE-2023-51766: Exim: SMTP smuggling",
          "tags": [
            "mailing-list"
          ],
          "url": "http://www.openwall.com/lists/oss-security/2024/01/01/2"
        },
        {
          "name": "[oss-security] 20240101 Re: CVE-2023-51766: Exim: SMTP smuggling",
          "tags": [
            "mailing-list"
          ],
          "url": "http://www.openwall.com/lists/oss-security/2024/01/01/3"
        },
        {
          "url": "https://www.youtube.com/watch?v=V8KPV96g1To"
        },
        {
          "name": "[debian-lts-announce] 20240105 [SECURITY] [DLA 3708-1] exim4 security update",
          "tags": [
            "mailing-list"
          ],
          "url": "https://lists.debian.org/debian-lts-announce/2024/01/msg00002.html"
        },
        {
          "name": "FEDORA-2024-1ef6197a49",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/QPDWHJPABVJCXDSNELSSVTIVAJU2MDUQ/"
        },
        {
          "name": "FEDORA-2024-e0841c83bb",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ORN7OKEQPPBKUHYRQ6LR5PSNBQVDHAWB/"
        },
        {
          "url": "https://lwn.net/Articles/956533/"
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
    "assignerShortName": "mitre",
    "cveId": "CVE-2023-51766",
    "datePublished": "2023-12-24T00:00:00.000Z",
    "dateReserved": "2023-12-24T00:00:00.000Z",
    "dateUpdated": "2025-11-04T18:21:35.998Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.