CVE-2025-5994

Estado: AplazadaAlta (8.7)—

A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies.

CVSS

Versión: 4.0
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/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:U/V:C/RE:X/U:X
Puntuación base: 8.7

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.20%
Percentil entre todas las CVEs puntuadas: 9
Fecha de la puntuación: 5/10/2026

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 access85 %
Impacto principalT1565.002 Transmitted Data Manipulationimpact75 %
Impacto secundarioT1498.002 Reflection Amplificationimpact70 %

Vulnerabilidad de envenenamiento de caché DNS explotable remotamente sin autenticación ni interacción (AV:N, PR:N, UI:N). Impacto en integridad de datos (VI:H) mediante inyección de respuestas falsas; potencial para DoS de DNS y suplantación.

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 Encrypt Sensitive Information

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Unbound — Unbound^AI

CWE

CWE-349

Referencias

JSON original (NVD)

Mostrar

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          "options": [
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  "published": "2025-07-16T15:15:33.490",
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      "source": "sep@nlnetlabs.nl"
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      "lang": "en",
      "value": "A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies."
    },
    {
      "lang": "es",
      "value": "Se ha descubierto una vulnerabilidad de envenenamiento de caché multiproveedor, denominada \"Ataque Rebirthday\", en resolutores de caché compatibles con EDNS Client Subnet (ECS). Unbound también es vulnerable cuando se compila con compatibilidad con ECS (es decir, con \"--enable-subnet\") y se configura para enviar información de ECS junto con consultas a servidores de nombres ascendentes (es decir, se utiliza al menos una de las opciones \"send-client-subnet\", \"client-subnet-zone\" o \"client-subnet-always-forward\"). Los resolutores compatibles con ECS deben segregar las consultas salientes para adaptarlas a la diferente información de ECS saliente. Esto expone a los resolutores a un ataque de paradoja de cumpleaños (Ataque Rebirthday), que intenta coincidir con el ID de transacción DNS para almacenar en caché respuestas tóxicas que no sean de ECS."
    }
  ],
  "lastModified": "2026-06-17T09:49:10.473",
  "sourceIdentifier": "sep@nlnetlabs.nl"
}