FKIE_CVE-2020-25687
Vulnerability from fkie_nvd - Published: 2021-01-20 17:15 - Updated: 2026-06-17 03:07
Severity
Summary
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.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| thekelleys | dnsmasq | * | |
| fedoraproject | fedora | 32 | |
| fedoraproject | fedora | 33 | |
| debian | debian_linux | 9.0 | |
| debian | debian_linux | 10.0 |
{
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"vendor": "n/a",
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"version": "dnsmasq 2.83"
}
]
}
],
"source": "secalert@redhat.com"
}
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"descriptions": [
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"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 encontr\u00f3 un fallo en dnsmasq versiones anteriores a 2.83.\u0026#xa0;Se detect\u00f3 un desbordamiento del b\u00fafer en la regi\u00f3n heap de la memoria en dnsmasq cuando DNSSEC est\u00e1 habilitado y antes de comprobar las entradas DNS recibidas.\u0026#xa0;Este fallo permite a un atacante remoto, que puede crear respuestas DNS v\u00e1lidas, causar un desbordamiento en una memoria asignada a la pila.\u0026#xa0;Este fallo es causado por una falta de comprobaci\u00f3n de longitud en la funci\u00f3n rfc1035.c:extract_name(), que podr\u00eda ser abusado para hacer que el c\u00f3digo ejecutar memcpy() con un tama\u00f1o negativo en sort_rrset() y causar un bloqueo en dnsmasq, resultando en una denegaci\u00f3n de servicio.\u0026#xa0;La mayor amenaza de esta vulnerabilidad es la disponibilidad del sistema"
}
],
"id": "CVE-2020-25687",
"lastModified": "2026-06-17T03:07:07.813",
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"published": "2021-01-20T17:15:13.060",
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"url": "https://www.kb.cert.org/vuls/id/434904"
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}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- 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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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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