ubuntu-cve-2023-51766
Vulnerability from osv_ubuntu
Published
2023-12-24 06:15
Modified
2026-06-04 00:00
Summary
Details

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 . but some other popular e-mail servers do not.

Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "exim4",
            "binary_version": "4.82-3ubuntu2.4+esm9"
          },
          {
            "binary_name": "exim4-base",
            "binary_version": "4.82-3ubuntu2.4+esm9"
          },
          {
            "binary_name": "exim4-config",
            "binary_version": "4.82-3ubuntu2.4+esm9"
          },
          {
            "binary_name": "exim4-daemon-heavy",
            "binary_version": "4.82-3ubuntu2.4+esm9"
          },
          {
            "binary_name": "exim4-daemon-light",
            "binary_version": "4.82-3ubuntu2.4+esm9"
          },
          {
            "binary_name": "eximon4",
            "binary_version": "4.82-3ubuntu2.4+esm9"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:14.04:LTS",
        "name": "exim4",
        "purl": "pkg:deb/ubuntu/exim4@4.82-3ubuntu2.4+esm9?arch=source\u0026distro=esm-infra-legacy/trusty"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.82-3ubuntu2.4+esm9"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.80-7ubuntu3",
        "4.80-7ubuntu4",
        "4.80-9ubuntu1",
        "4.80-9ubuntu2",
        "4.82-3ubuntu1",
        "4.82-3ubuntu2",
        "4.82-3ubuntu2.1",
        "4.82-3ubuntu2.2",
        "4.82-3ubuntu2.3",
        "4.82-3ubuntu2.4",
        "4.82-3ubuntu2.4+esm1",
        "4.82-3ubuntu2.4+esm2",
        "4.82-3ubuntu2.4+esm3",
        "4.82-3ubuntu2.4+esm4",
        "4.82-3ubuntu2.4+esm6",
        "4.82-3ubuntu2.4+esm7",
        "4.82-3ubuntu2.4+esm8"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "exim4",
            "binary_version": "4.86.2-2ubuntu2.6+esm6"
          },
          {
            "binary_name": "exim4-base",
            "binary_version": "4.86.2-2ubuntu2.6+esm6"
          },
          {
            "binary_name": "exim4-config",
            "binary_version": "4.86.2-2ubuntu2.6+esm6"
          },
          {
            "binary_name": "exim4-daemon-heavy",
            "binary_version": "4.86.2-2ubuntu2.6+esm6"
          },
          {
            "binary_name": "exim4-daemon-light",
            "binary_version": "4.86.2-2ubuntu2.6+esm6"
          },
          {
            "binary_name": "eximon4",
            "binary_version": "4.86.2-2ubuntu2.6+esm6"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:16.04:LTS",
        "name": "exim4",
        "purl": "pkg:deb/ubuntu/exim4@4.86.2-2ubuntu2.6+esm6?arch=source\u0026distro=esm-infra/xenial"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.86.2-2ubuntu2.6+esm6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.86-3ubuntu1",
        "4.86-7ubuntu1",
        "4.86-7ubuntu2",
        "4.86-7ubuntu3",
        "4.86.2-2ubuntu1",
        "4.86.2-2ubuntu2",
        "4.86.2-2ubuntu2.1",
        "4.86.2-2ubuntu2.2",
        "4.86.2-2ubuntu2.3",
        "4.86.2-2ubuntu2.4",
        "4.86.2-2ubuntu2.5",
        "4.86.2-2ubuntu2.6",
        "4.86.2-2ubuntu2.6+esm1",
        "4.86.2-2ubuntu2.6+esm2",
        "4.86.2-2ubuntu2.6+esm4",
        "4.86.2-2ubuntu2.6+esm5"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "exim4",
            "binary_version": "4.90.1-1ubuntu1.10+esm3"
          },
          {
            "binary_name": "exim4-base",
            "binary_version": "4.90.1-1ubuntu1.10+esm3"
          },
          {
            "binary_name": "exim4-config",
            "binary_version": "4.90.1-1ubuntu1.10+esm3"
          },
          {
            "binary_name": "exim4-daemon-heavy",
            "binary_version": "4.90.1-1ubuntu1.10+esm3"
          },
          {
            "binary_name": "exim4-daemon-light",
            "binary_version": "4.90.1-1ubuntu1.10+esm3"
          },
          {
            "binary_name": "eximon4",
            "binary_version": "4.90.1-1ubuntu1.10+esm3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "exim4",
        "purl": "pkg:deb/ubuntu/exim4@4.90.1-1ubuntu1.10+esm3?arch=source\u0026distro=esm-infra/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.90.1-1ubuntu1.10+esm3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.89-5ubuntu1",
        "4.89-9ubuntu1",
        "4.89-9ubuntu2",
        "4.89-9ubuntu3",
        "4.89-9ubuntu4",
        "4.90.1-1ubuntu1",
        "4.90.1-1ubuntu1.1",
        "4.90.1-1ubuntu1.2",
        "4.90.1-1ubuntu1.3",
        "4.90.1-1ubuntu1.4",
        "4.90.1-1ubuntu1.5",
        "4.90.1-1ubuntu1.8",
        "4.90.1-1ubuntu1.9",
        "4.90.1-1ubuntu1.10",
        "4.90.1-1ubuntu1.10+esm1",
        "4.90.1-1ubuntu1.10+esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "exim4",
            "binary_version": "4.93-13ubuntu1.10"
          },
          {
            "binary_name": "exim4-base",
            "binary_version": "4.93-13ubuntu1.10"
          },
          {
            "binary_name": "exim4-config",
            "binary_version": "4.93-13ubuntu1.10"
          },
          {
            "binary_name": "exim4-daemon-heavy",
            "binary_version": "4.93-13ubuntu1.10"
          },
          {
            "binary_name": "exim4-daemon-light",
            "binary_version": "4.93-13ubuntu1.10"
          },
          {
            "binary_name": "eximon4",
            "binary_version": "4.93-13ubuntu1.10"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "exim4",
        "purl": "pkg:deb/ubuntu/exim4@4.93-13ubuntu1.10?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.93-13ubuntu1.10"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.92.1-1ubuntu3",
        "4.92.1-1ubuntu4",
        "4.93~RC2-1ubuntu1",
        "4.93-9ubuntu1",
        "4.93-11ubuntu1",
        "4.93-12ubuntu1",
        "4.93-13ubuntu1",
        "4.93-13ubuntu1.1",
        "4.93-13ubuntu1.5",
        "4.93-13ubuntu1.6",
        "4.93-13ubuntu1.7",
        "4.93-13ubuntu1.8",
        "4.93-13ubuntu1.9"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "exim4",
            "binary_version": "4.95-4ubuntu2.5"
          },
          {
            "binary_name": "exim4-base",
            "binary_version": "4.95-4ubuntu2.5"
          },
          {
            "binary_name": "exim4-config",
            "binary_version": "4.95-4ubuntu2.5"
          },
          {
            "binary_name": "exim4-daemon-heavy",
            "binary_version": "4.95-4ubuntu2.5"
          },
          {
            "binary_name": "exim4-daemon-light",
            "binary_version": "4.95-4ubuntu2.5"
          },
          {
            "binary_name": "eximon4",
            "binary_version": "4.95-4ubuntu2.5"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "exim4",
        "purl": "pkg:deb/ubuntu/exim4@4.95-4ubuntu2.5?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.95-4ubuntu2.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.94.2-7ubuntu2",
        "4.95-2ubuntu2",
        "4.95-4ubuntu1",
        "4.95-4ubuntu2",
        "4.95-4ubuntu2.1",
        "4.95-4ubuntu2.2",
        "4.95-4ubuntu2.3",
        "4.95-4ubuntu2.4"
      ]
    }
  ],
  "aliases": [],
  "details": "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.",
  "id": "UBUNTU-CVE-2023-51766",
  "modified": "2026-06-04T00:00:21Z",
  "published": "2023-12-24T06:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2023-51766"
    },
    {
      "type": "REPORT",
      "url": "https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/"
    },
    {
      "type": "REPORT",
      "url": "https://www.openwall.com/lists/oss-security/2023/12/21/6"
    },
    {
      "type": "REPORT",
      "url": "https://exim.org/static/doc/security/CVE-2023-51766.txt"
    },
    {
      "type": "REPORT",
      "url": "https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5"
    },
    {
      "type": "REPORT",
      "url": "https://git.exim.org/exim.git/commit/4596719398f6f2365bed563aafd757a6433ce7b4"
    },
    {
      "type": "REPORT",
      "url": "https://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-6611-1"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2023-51766"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8382-1"
    }
  ],
  "related": [
    "USN-6611-1",
    "USN-8382-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2023-51766"
  ]
}



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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.
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  • 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.


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