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CVE-2026-45945

Estado: ModificadaAlta (8.8)—

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

iommu/vt-d: Fix race condition during PASID entry replacement

The Intel VT-d PASID table entry is 512 bits (64 bytes). When replacing an active PASID entry (e.g., during domain replacement), the current implementation calculates a new entry on the stack and copies it to the table using a single structure assignment.

Because the hardware may fetch the 512-bit PASID entry in multiple 128-bit chunks, updating the entire entry while it is active (Present bit set) risks a "torn" read. In this scenario, the IOMMU hardware could observe an inconsistent state — partially new data and partially old data — leading to unpredictable behavior or spurious faults.

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Fix this by removing the unsafe "replace" helpers and following the "clear-then-update" flow, which ensures the Present bit is cleared and the required invalidation handshake is completed before the new configuration is applied.

Detalles técnicos trazas, registros y código del informe original
        struct pasid_entry *pte, new_pte;

        pte = intel_pasid_get_entry(dev, pasid);
        pasid_pte_config_first_level(iommu, &new_pte, ...);
        *pte = new_pte;

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 de escalada local con PR:L (requiere acceso ya como usuario local) que permite manipular tablas PASID del IOMMU en kernel Linux, ganando control de privilegios o causando denegación de servicio por inconsistencia de hardware.

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)

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{
  "id": "CVE-2026-45945",
  "cveTags": [],
  "metrics": {
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          "version": "3.1",
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          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H",
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  "published": "2026-05-27T14:17:10.790",
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      "source": "nvd@nist.gov",
      "description": [
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          "value": "CWE-362"
        }
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  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Fix race condition during PASID entry replacement\n\nThe Intel VT-d PASID table entry is 512 bits (64 bytes). When replacing\nan active PASID entry (e.g., during domain replacement), the current\nimplementation calculates a new entry on the stack and copies it to the\ntable using a single structure assignment.\n\n        struct pasid_entry *pte, new_pte;\n\n        pte = intel_pasid_get_entry(dev, pasid);\n        pasid_pte_config_first_level(iommu, &new_pte, ...);\n        *pte = new_pte;\n\nBecause the hardware may fetch the 512-bit PASID entry in multiple\n128-bit chunks, updating the entire entry while it is active (Present\nbit set) risks a \"torn\" read. In this scenario, the IOMMU hardware\ncould observe an inconsistent state — partially new data and partially\nold data — leading to unpredictable behavior or spurious faults.\n\nFix this by removing the unsafe \"replace\" helpers and following the\n\"clear-then-update\" flow, which ensures the Present bit is cleared and\nthe required invalidation handshake is completed before the new\nconfiguration is applied."
    }
  ],
  "lastModified": "2026-07-18T16:17:13.390",
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