CVE-2018-6789

Estado: AnalizadaCrítica (9.8)⚠ Explotación activa💥 Exploit

An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1. By sending a handcrafted message, a buffer overflow may happen. This can be used to execute code remotely.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 9.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 82%
Percentil entre todas las CVEs puntuadas: 100
Fecha de la puntuación: 7/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

CISA KEV — explotada activamente

Añadida al catálogo: 3/11/2021
Plazo de remediación: 3/5/2022
Uso conocido en ransomware: Known

💥 Exploits públicos

Hay código de explotación o plantillas de detección públicos. No es lo mismo que explotación activa confirmada (KEV), pero aumenta el riesgo: parchee con prioridad.

Publicado en Exploit-DB · exim 4.90 - Remote Code Execution (24/10/2018)
Publicado en Exploit-DB · Exim < 4.90.1 - 'base64d' Remote Code Execution (2/5/2018)
Prueba de concepto en GitHub (no verificada) · Lista de pruebas de concepto en GitHub

⚠️ Las pruebas de concepto de GitHub no están verificadas: algunas son falsas o contienen malware. No las ejecute nunca fuera de un laboratorio aislado.

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access95 %
Impacto principalT1059 Command and Scripting Interpreterexecution90 %

CVE-2018-6789: buffer overflow en listener SMTP de Exim sin autenticación previa (AV:N/PR:N) permite ejecución remota de código (RCE). T1190 por exposición de servicio SMTP; T1059 por ejecución de comandos directo tras desbordamiento.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Privileged Account Management Vulnerability Scanning Restrict Web-Based Content Network Segmentation Limit Software Installation Limit Access to Resource Over Network

Tecnologías afectadas (3)

Canonical — Ubuntu Linux Debian — Debian Linux Exim — Exim

CWE

CWE-120
CWE-120

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2018-6789",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2018-6789",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "active"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2025-02-07T14:03:40.827397Z"
        }
      }
    ],
    "cvssMetricV2": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "version": "2.0",
          "baseScore": 7.5,
          "accessVector": "NETWORK",
          "vectorString": "AV:N/AC:L/Au:N/C:P/I:P/A:P",
          "authentication": "NONE",
          "integrityImpact": "PARTIAL",
          "accessComplexity": "LOW",
          "availabilityImpact": "PARTIAL",
          "confidentialityImpact": "PARTIAL"
        },
        "acInsufInfo": false,
        "impactScore": 6.4,
        "baseSeverity": "HIGH",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 10,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": false
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      },
      {
        "type": "Secondary",
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 9.8,
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 3.9
      }
    ]
  },
  "affected": [
    {
      "source": "cve@mitre.org",
      "affectedData": [
        {
          "vendor": "n/a",
          "product": "n/a",
          "versions": [
            {
              "status": "affected",
              "version": "n/a"
            }
          ]
        }
      ]
    }
  ],
  "published": "2018-02-08T23:29:01.170",
  "references": [
    {
      "url": "http://openwall.com/lists/oss-security/2018/02/10/2",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html",
      "tags": [
        "Exploit",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "http://www.openwall.com/lists/oss-security/2018/02/07/2",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "http://www.securityfocus.com/bid/103049",
      "tags": [
        "Broken Link",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "http://www.securitytracker.com/id/1040461",
      "tags": [
        "Broken Link",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://exim.org/static/doc/security/CVE-2018-6789.txt",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1",
      "tags": [
        "Patch"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://lists.debian.org/debian-lts-announce/2018/02/msg00009.html",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://usn.ubuntu.com/3565-1/",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://www.debian.org/security/2018/dsa-4110",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://www.exploit-db.com/exploits/44571/",
      "tags": [
        "Exploit",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "https://www.exploit-db.com/exploits/45671/",
      "tags": [
        "Exploit",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "cve@mitre.org"
    },
    {
      "url": "http://openwall.com/lists/oss-security/2018/02/10/2",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://packetstormsecurity.com/files/162959/Exim-base64d-Buffer-Overflow.html",
      "tags": [
        "Exploit",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://www.openwall.com/lists/oss-security/2018/02/07/2",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://www.securityfocus.com/bid/103049",
      "tags": [
        "Broken Link",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "http://www.securitytracker.com/id/1040461",
      "tags": [
        "Broken Link",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://devco.re/blog/2018/03/06/exim-off-by-one-RCE-exploiting-CVE-2018-6789-en/",
      "tags": [
        "Exploit",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://exim.org/static/doc/security/CVE-2018-6789.txt",
      "tags": [
        "Vendor Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://git.exim.org/exim.git/commit/cf3cd306062a08969c41a1cdd32c6855f1abecf1",
      "tags": [
        "Patch"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://lists.debian.org/debian-lts-announce/2018/02/msg00009.html",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://usn.ubuntu.com/3565-1/",
      "tags": [
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.debian.org/security/2018/dsa-4110",
      "tags": [
        "Mailing List",
        "Third Party Advisory"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.exploit-db.com/exploits/44571/",
      "tags": [
        "Exploit",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.exploit-db.com/exploits/45671/",
      "tags": [
        "Exploit",
        "Third Party Advisory",
        "VDB Entry"
      ],
      "source": "af854a3a-2127-422b-91ae-364da2661108"
    },
    {
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-6789",
      "tags": [
        "US Government Resource"
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"
    }
  ],
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-120"
        }
      ]
    },
    {
      "type": "Secondary",
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "description": [
        {
          "lang": "en",
          "value": "CWE-120"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "An issue was discovered in the base64d function in the SMTP listener in Exim before 4.90.1. By sending a handcrafted message, a buffer overflow may happen. This can be used to execute code remotely."
    },
    {
      "lang": "es",
      "value": "Se ha descubierto un problema en la función base64d en el escuchador SMTP en Exim, en versiones anteriores a la 4.90.1. Al enviar un mensaje manipulado, podría ocurrir un desbordamiento de búfer. Esto puede emplearse para ejecutar código de forma remota."
    }
  ],
  "lastModified": "2026-06-17T02:02:17.180",
  "cisaActionDue": "2022-05-03",
  "cisaExploitAdd": "2021-11-03",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "EC35DD1C-8421-443D-9EBC-73F1C7B7306E",
              "versionEndExcluding": "4.90.1"
            }
          ],
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:debian:debian_linux:7.0:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "16F59A04-14CF-49E2-9973-645477EA09DA"
            },
            {
              "criteria": "cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "C11E6FB0-C8C0-4527-9AA0-CB9B316F8F43"
            },
            {
              "criteria": "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "DEECE5FC-CACF-4496-A3E7-164736409252"
            }
          ],
          "operator": "OR"
        }
      ]
    },
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:esm:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "815D70A8-47D3-459C-A32C-9FEACA0659D1"
            },
            {
              "criteria": "cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:esm:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "7A5301BF-1402-4BE0-A0F8-69FBE79BC6D6"
            },
            {
              "criteria": "cpe:2.3:o:canonical:ubuntu_linux:17.10:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "9070C9D8-A14A-467F-8253-33B966C16886"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "cve@mitre.org",
  "cisaRequiredAction": "Apply updates per vendor instructions.",
  "cisaVulnerabilityName": "Exim Buffer Overflow Vulnerability"
}