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CVE-2026-21869

Estado: AnalizadaCrítica (9.8)—

llama.cpp is an inference of several LLM models in C/C++. In commits 55d4206c8 and prior, the n_discard parameter is parsed directly from JSON input in the llama.cpp server's completion endpoints without validation to ensure it's non-negative. When a negative value is supplied and the context fills up, llama_memory_seq_rm/add receives a reversed range and negative offset, causing out-of-bounds memory writes in the token evaluation loop. This deterministic memory corruption can crash the process or enable remote code execution (RCE). There is no fix at the time of publication.

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).

🎯 Técnicas ATT&CK

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

Vulnerabilidad en servidor expuesto (llama.cpp): parámetro n_discard sin validación en endpoints JSON permite escritura fuera de límites (CWE-787) sin autenticación (PR:N, UI:N). Resulta en ejecución de código remoto determinista o negación de servicio.

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 ManagementFilter Network TrafficVulnerability ScanningRestrict Web-Based ContentNetwork SegmentationLimit Software Installation

Tecnologías afectadas (1)

Ggml — Llama.cpp

CWE

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-21869",
  "cveTags": [],
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          "role": "CISA Coordinator",
          "options": [
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              "exploitation": "poc"
            },
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              "automatable": "no"
            },
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              "technicalImpact": "total"
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          "version": "2.0.3",
          "timestamp": "2026-01-08T19:15:25.248439Z"
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      "description": [
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          "value": "CWE-787"
        }
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  ],
  "descriptions": [
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      "lang": "en",
      "value": "llama.cpp is an inference of several LLM models in C/C++. In commits 55d4206c8 and prior, the n_discard parameter is parsed directly from JSON input in the llama.cpp server's completion endpoints without validation to ensure it's non-negative. When a negative value is supplied and the context fills up, llama_memory_seq_rm/add receives a reversed range and negative offset, causing out-of-bounds memory writes in the token evaluation loop. This deterministic memory corruption can crash the process or enable remote code execution (RCE). There is no fix at the time of publication."
    },
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      "value": "llama.cpp es una inferencia de varios modelos LLM en C/C++. En los commits 55d4206c8 y anteriores, el parámetro n_discard se analiza directamente de la entrada JSON en los puntos finales de completado del servidor de llama.cpp sin validación para asegurar que no sea negativo. Cuando se suministra un valor negativo y el contexto se llena, llama_memory_seq_rm/add recibe un rango invertido y un desplazamiento negativo, causando escrituras de memoria fuera de límites en el bucle de evaluación de tokens. Esta corrupción de memoria determinista puede bloquear el proceso o permitir la ejecución remota de código (RCE). No hay una solución en el momento de la publicación."
    }
  ],
  "lastModified": "2026-06-17T10:19:03.657",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
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