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CVE-2020-25687

Estado: ModificadaMedia (5.9)—

A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. This flaw allows a remote attacker, who can create valid DNS replies, to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code execute memcpy() with a negative size in sort_rrset() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.

CVSS

Probabilidad de explotación (EPSS)

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).

Tecnologías afectadas (3)

Debian — Debian LinuxFedoraproject — FedoraThekelleys — Dnsmasq

CWE

Referencias

JSON original (NVD)

Mostrar
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  "id": "CVE-2020-25687",
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          "vectorString": "AV:N/AC:M/Au:N/C:N/I:N/A:C",
          "authentication": "NONE",
          "integrityImpact": "NONE",
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          "availabilityImpact": "COMPLETE",
          "confidentialityImpact": "NONE"
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      "source": "secalert@redhat.com",
      "description": [
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          "value": "CWE-122"
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    {
      "lang": "en",
      "value": "A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. This flaw allows a remote attacker, who can create valid DNS replies, to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code execute memcpy() with a negative size in sort_rrset() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability."
    },
    {
      "lang": "es",
      "value": "Se encontró un fallo en dnsmasq versiones anteriores a 2.83. Se detectó un desbordamiento del búfer en la región heap de la memoria en dnsmasq cuando DNSSEC está habilitado y antes de comprobar las entradas DNS recibidas. Este fallo permite a un atacante remoto, que puede crear respuestas DNS válidas, causar un desbordamiento en una memoria asignada a la pila. Este fallo es causado por una falta de comprobación de longitud en la función  rfc1035.c:extract_name(), que podría ser abusado para hacer que el código ejecutar memcpy() con un tamaño negativo en sort_rrset() y causar un bloqueo en dnsmasq, resultando en una denegación de servicio. La mayor amenaza de esta vulnerabilidad es la disponibilidad del sistema"
    }
  ],
  "lastModified": "2026-06-17T03:07:07.813",
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}