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CVE-2026-64186

Estado: AnalizadaAlta (7.1)—

In the Linux kernel, the following vulnerability has been resolved:

iommu/amd: Remove latent out-of-bounds access in IOMMU debugfs

In iommu_mmio_write() and iommu_capability_write(), the variables dbg_mmio_offset and dbg_cap_offset are declared as int. However, they are populated using kstrtou32_from_user(). If a user provides a sufficiently large value, it can become a negative integer.

Prior to this patch, the AMD IOMMU debugfs implementation was already protected by different mechanisms.

Replace kstrtou32_from_user() with kstrtos32_from_user() to parse the input, and check for negative values to explicitly prevent out-of-bounds memory accesses directly in iommu_mmio_write() and iommu_capability_write().

Detalles técnicos trazas, registros y código del informe original
1. #define OFS_IN_SZ 8 ensures the user string <= 8 bytes, so
   e.g. 0xffffffff isn't a valid input.

  if (cnt > OFS_IN_SZ)
     return -EINVAL;

2. Implicit type promotion in iommu_mmio_write(), dbg_mmio_offset is int
   and iommu->mmio_phys_end is u64

  if (dbg_mmio_offset > iommu->mmio_phys_end - sizeof(u64))
      return -EINVAL;

3. The show handlers would currently catch the negative number and
   refuse to perform the read.

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.

Acceso local (AV:L) sin interacción de usuario permite leer memoria (C:H) e interrumpir servicios (A:H) mediante out-of-bounds en debugfs del IOMMU AMD; CWE-125 es lectura fuera de límites.

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

Threat Intelligence ProgramFilter Network TrafficExecution PreventionApplication Isolation and SandboxingExploit ProtectionUpdate Software

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/amd: Remove latent out-of-bounds access in IOMMU debugfs\n\nIn iommu_mmio_write() and iommu_capability_write(), the variables\ndbg_mmio_offset and dbg_cap_offset are declared as int. However, they\nare populated using kstrtou32_from_user(). If a user provides a\nsufficiently large value, it can become a negative integer.\n\nPrior to this patch, the AMD IOMMU debugfs implementation was already\nprotected by different mechanisms.\n\n1. #define OFS_IN_SZ 8 ensures the user string <= 8 bytes, so\n   e.g. 0xffffffff isn't a valid input.\n\n  if (cnt > OFS_IN_SZ)\n     return -EINVAL;\n\n2. Implicit type promotion in iommu_mmio_write(), dbg_mmio_offset is int\n   and iommu->mmio_phys_end is u64\n\n  if (dbg_mmio_offset > iommu->mmio_phys_end - sizeof(u64))\n      return -EINVAL;\n\n3. The show handlers would currently catch the negative number and\n   refuse to perform the read.\n\nReplace kstrtou32_from_user() with kstrtos32_from_user() to parse the\ninput, and check for negative values to explicitly prevent out-of-bounds\nmemory accesses directly in iommu_mmio_write() and\niommu_capability_write()."
    }
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  "lastModified": "2026-08-11T20:03:12.163",
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