CVE-2026-33278

Estado: ModificadaCrítica (9.1)—

NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown.

Leer descripción completaMostrar menos

A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure.

CVSS

Versión: 4.0
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Red
Puntuación base: 9.1

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 1.13%
Percentil entre todas las CVEs puntuadas: 65
Fecha de la puntuación: 6/10/2026

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).

🎯 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 access92 %
Impacto principalT1499.004 Application or System Exploitationimpact88 %

AV:N/PR:N/UI:N indica vulnerabilidad de red sin autenticación ni interacción del usuario en servicio DNS público (Unbound). El atacante controla una zona DNSSEC maliciosa para gatillar deep-copy y dereferencia de puntero dangling, causando crash DoS o posible RCE. CWE-416 (use-after-free) y CWE-672

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

Filter Network Traffic Vulnerability Scanning Privileged Account Management Network Segmentation Limit Access to Resource Over Network Application Isolation and Sandboxing

Tecnologías afectadas (1)

Nlnetlabs — Unbound

CWE

CWE-416, CWE-672
CWE-416

Referencias

JSON original (NVD)

Mostrar

{
  "id": "CVE-2026-33278",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-33278",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "yes"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-05-20T12:13:01.681597Z"
        }
      }
    ],
    "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": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 8.1,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "HIGH",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 2.2
      }
    ],
    "cvssMetricV40": [
      {
        "type": "Secondary",
        "source": "sep@nlnetlabs.nl",
        "cvssData": {
          "Safety": "NOT_DEFINED",
          "version": "4.0",
          "Recovery": "NOT_DEFINED",
          "baseScore": 9.1,
          "Automatable": "NOT_DEFINED",
          "attackVector": "NETWORK",
          "baseSeverity": "CRITICAL",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Red",
          "exploitMaturity": "UNREPORTED",
          "providerUrgency": "RED",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "attackRequirements": "NONE",
          "privilegesRequired": "NONE",
          "subIntegrityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "subAvailabilityImpact": "HIGH",
          "vulnAvailabilityImpact": "HIGH",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "subConfidentialityImpact": "HIGH",
          "vulnConfidentialityImpact": "HIGH",
          "confidentialityRequirement": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED"
        }
      }
    ]
  },
  "affected": [
    {
      "source": "sep@nlnetlabs.nl",
      "affectedData": [
        {
          "vendor": "NLnet Labs",
          "product": "Unbound",
          "versions": [
            {
              "status": "affected",
              "version": "1.19.1",
              "lessThan": "1.25.1",
              "versionType": "semver"
            }
          ],
          "defaultStatus": "unaffected"
        }
      ]
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "affectedData": [
        {
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:10.2"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 10",
          "versions": [
            {
              "status": "unaffected",
              "version": "0:1.24.2-7.el10_2.1",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "unbound",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:enterprise_linux:9"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 9",
          "versions": [
            {
              "status": "unaffected",
              "version": "0:1.24.2-3.el9_8.1",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "unbound",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:hummingbird:1"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat Hardened Images",
          "versions": [
            {
              "status": "unaffected",
              "version": "1.25.1-0.1.hum1",
              "lessThan": "*",
              "versionType": "rpm"
            }
          ],
          "packageName": "unbound-main",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "affected"
        },
        {
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:6"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 6",
          "packageName": "unbound",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "unknown"
        },
        {
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:7"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 7",
          "packageName": "unbound",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "unaffected"
        },
        {
          "cpes": [
            "cpe:/o:redhat:enterprise_linux:8"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat Enterprise Linux 8",
          "packageName": "unbound",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "unaffected"
        },
        {
          "cpes": [
            "cpe:/a:redhat:openshift:4"
          ],
          "vendor": "Red Hat",
          "product": "Red Hat OpenShift Container Platform 4",
          "packageName": "openshift/ose-rhel-coreos-9",
          "collectionURL": "https://access.redhat.com/downloads/content/package-browser/",
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-05-20T10:16:26.530",
  "references": [
    {
      "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-33278.txt",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ],
      "source": "sep@nlnetlabs.nl"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:19752",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:23231",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://access.redhat.com/errata/RHSA-2026:24369",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://access.redhat.com/security/cve/CVE-2026-33278",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2479808",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    },
    {
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33278.json",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "sep@nlnetlabs.nl",
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        },
        {
          "lang": "en",
          "value": "CWE-672"
        }
      ]
    },
    {
      "type": "Secondary",
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "NLnet Labs Unbound 1.19.1 up to and including version 1.25.0 has a vulnerability in the DNSSEC validator that enables denial of service and possible remote code execution as a result of deep copying a data structure and erroneously overwriting a destination pointer. An adversary can exploit the vulnerability by controlling a malicious signed zone and querying a vulnerable Unbound. When DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1), Unbound deep-copies response messages to preserve them across memory region teardown. A struct-assignment bug overwrites the destination's pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. Unbound 1.25.1 contains a patch with a fix to preserve the correct pointer when deep copying the data structure."
    },
    {
      "lang": "es",
      "value": "NLnet Labs Unbound 1.19.1 hasta la versión 1.25.0 inclusive tiene una vulnerabilidad en el validador DNSSEC que permite la denegación de servicio y posible ejecución remota de código como resultado de la copia profunda de una estructura de datos y la sobrescritura errónea de un puntero de destino. Un adversario puede explotar la vulnerabilidad controlando una zona firmada maliciosa y consultando un Unbound vulnerable. Cuando las subconsultas DS necesitan suspender la validación debido al agotamiento del presupuesto computacional de NSEC3 (introducido en Unbound 1.19.1), Unbound realiza copias profundas de los mensajes de respuesta para preservarlos durante la desasignación de la región de memoria. Un error de asignación de estructura sobrescribe el puntero del destino con el puntero del origen. Después de que se libera la región de la subconsulta, el validador reanudado desreferencia este puntero colgante, lo que provoca un fallo o potencialmente permite la ejecución de código arbitrario. Unbound 1.25.1 contiene un parche con una corrección para preservar el puntero correcto al realizar la copia profunda de la estructura de datos."
    }
  ],
  "lastModified": "2026-08-25T13:18:30.537",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:nlnetlabs:unbound:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "5C330C7D-8CBA-407E-9C85-8BB7D5A97797",
              "versionEndExcluding": "1.25.1",
              "versionStartIncluding": "1.19.1"
            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "sep@nlnetlabs.nl"
}