{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Clear Present bit before tearing down PASID entry\n\nThe Intel VT-d Scalable Mode PASID table entry consists of 512 bits (64\nbytes). When tearing down an entry, the current implementation zeros the\nentire 64-byte structure immediately using multiple 64-bit writes.\n\nSince the IOMMU hardware may fetch these 64 bytes using multiple\ninternal transactions (e.g., four 128-bit bursts), updating or zeroing\nthe entire entry while it is active (P=1) risks a \"torn\" read. If a\nhardware fetch occurs simultaneously with the CPU zeroing the entry, the\nhardware could observe an inconsistent state, leading to unpredictable\nbehavior or spurious faults.\n\nFollow the \"Guidance to Software for Invalidations\" in the VT-d spec\n(Section 6.5.3.3) by implementing the recommended ownership handshake:\n\n1. Clear only the \u0027Present\u0027 (P) bit of the PASID entry.\n2. Use a dma_wmb() to ensure the cleared bit is visible to hardware\n   before proceeding.\n3. Execute the required invalidation sequence (PASID cache, IOTLB, and\n   Device-TLB flush) to ensure the hardware has released all cached\n   references.\n4. Only after the flushes are complete, zero out the remaining fields\n   of the PASID entry.\n\nAlso, add a dma_wmb() in pasid_set_present() to ensure that all other\nfields of the PASID entry are visible to the hardware before the Present\nbit is set."
    }
  ],
  "id": "CVE-2026-45894",
  "lastModified": "2026-05-27T14:48:31.480",
  "metrics": {},
  "published": "2026-05-27T14:17:03.610",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/75ed00055c059dedc47b5daaaa2f8a7a019138ff"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/821807c167b7b48a41b95b6607c6b9f97600f7d9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/949d71666e9dd19f21e7b4b53a88cd2c5b902858"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a84d30e8d2bacd21782a6481158b7c9c552f4868"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-45894"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-27T14:17:03Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Clear Present bit before tearing down PASID entry\n\nThe Intel VT-d Scalable Mode PASID table entry consists of 512 bits (64\nbytes). When tearing down an entry, the current implementation zeros the\nentire 64-byte structure immediately using multiple 64-bit writes.\n\nSince the IOMMU hardware may fetch these 64 bytes using multiple\ninternal transactions (e.g., four 128-bit bursts), updating or zeroing\nthe entire entry while it is active (P=1) risks a \"torn\" read. If a\nhardware fetch occurs simultaneously with the CPU zeroing the entry, the\nhardware could observe an inconsistent state, leading to unpredictable\nbehavior or spurious faults.\n\nFollow the \"Guidance to Software for Invalidations\" in the VT-d spec\n(Section 6.5.3.3) by implementing the recommended ownership handshake:\n\n1. Clear only the \u0027Present\u0027 (P) bit of the PASID entry.\n2. Use a dma_wmb() to ensure the cleared bit is visible to hardware\n   before proceeding.\n3. Execute the required invalidation sequence (PASID cache, IOTLB, and\n   Device-TLB flush) to ensure the hardware has released all cached\n   references.\n4. Only after the flushes are complete, zero out the remaining fields\n   of the PASID entry.\n\nAlso, add a dma_wmb() in pasid_set_present() to ensure that all other\nfields of the PASID entry are visible to the hardware before the Present\nbit is set.",
  "id": "GHSA-8pm8-q9qq-gqgp",
  "modified": "2026-05-27T15:33:15Z",
  "published": "2026-05-27T15:33:15Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45894"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/75ed00055c059dedc47b5daaaa2f8a7a019138ff"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/821807c167b7b48a41b95b6607c6b9f97600f7d9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/949d71666e9dd19f21e7b4b53a88cd2c5b902858"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a84d30e8d2bacd21782a6481158b7c9c552f4868"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

{
  "document": {
    "category": "csaf_vex",
    "csaf_version": "2.0",
    "distribution": {
      "text": "Public",
      "tlp": {
        "label": "WHITE",
        "url": "https://www.first.org/tlp/"
      }
    },
    "lang": "en-US",
    "notes": [
      {
        "category": "general",
        "text": "To determine the support lifecycle for your software, see the Microsoft Support Lifecycle: https://support.microsoft.com/lifecycle",
        "title": "Additional Resources"
      },
      {
        "category": "legal_disclaimer",
        "text": "The information provided in the Microsoft Knowledge Base is provided \\\"as is\\\" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.",
        "title": "Disclaimer"
      }
    ],
    "publisher": {
      "category": "vendor",
      "contact_details": "secure@microsoft.com",
      "name": "Microsoft Security Response Center",
      "namespace": "https://msrc.microsoft.com"
    },
    "references": [
      {
        "category": "self",
        "summary": "CVE-2026-45894 iommu/vt-d: Clear Present bit before tearing down PASID entry - VEX",
        "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-45894.json"
      },
      {
        "category": "external",
        "summary": "Microsoft Support Lifecycle",
        "url": "https://support.microsoft.com/lifecycle"
      },
      {
        "category": "external",
        "summary": "Common Vulnerability Scoring System",
        "url": "https://www.first.org/cvss"
      }
    ],
    "title": "iommu/vt-d: Clear Present bit before tearing down PASID entry",
    "tracking": {
      "current_release_date": "2026-05-29T01:43:18.000Z",
      "generator": {
        "date": "2026-05-29T07:23:45.789Z",
        "engine": {
          "name": "MSRC Generator",
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      "id": "msrc_CVE-2026-45894",
      "initial_release_date": "2026-05-02T00:00:00.000Z",
      "revision_history": [
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          "date": "2026-05-28T01:04:10.000Z",
          "legacy_version": "1",
          "number": "1",
          "summary": "Information published."
        },
        {
          "date": "2026-05-28T14:46:53.000Z",
          "legacy_version": "1.1",
          "number": "2",
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        },
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          "legacy_version": "2",
          "number": "3",
          "summary": "Information published."
        }
      ],
      "status": "final",
      "version": "3"
    }
  },
  "product_tree": {
    "branches": [
      {
        "branches": [
          {
            "branches": [
              {
                "category": "product_version",
                "name": "3.0",
                "product": {
                  "name": "Azure Linux 3.0",
                  "product_id": "17084"
                }
              }
            ],
            "category": "product_name",
            "name": "Azure Linux"
          },
          {
            "branches": [
              {
                "category": "product_version_range",
                "name": "azl3 kernel 0:6.6.139.1-1.azl3",
                "product": {
                  "name": "azl3 kernel 0:6.6.139.1-1.azl3",
                  "product_id": "1"
                }
              }
            ],
            "category": "product_name",
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          }
        ],
        "category": "vendor",
        "name": "Microsoft"
      }
    ],
    "relationships": [
      {
        "category": "default_component_of",
        "full_product_name": {
          "name": "azl3 kernel 0:6.6.139.1-1.azl3 as a component of Azure Linux 3.0",
          "product_id": "17084-1"
        },
        "product_reference": "1",
        "relates_to_product_reference": "17084"
      }
    ]
  },
  "vulnerabilities": [
    {
      "cve": "CVE-2026-45894",
      "notes": [
        {
          "category": "general",
          "text": "Linux",
          "title": "Assigning CNA"
        }
      ],
      "product_status": {
        "known_affected": [
          "17084-1"
        ]
      },
      "references": [
        {
          "category": "self",
          "summary": "CVE-2026-45894 iommu/vt-d: Clear Present bit before tearing down PASID entry - VEX",
          "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-45894.json"
        }
      ],
      "remediations": [
        {
          "category": "none_available",
          "date": "2026-05-28T01:04:10.000Z",
          "details": "There is no fix available for this vulnerability as of now",
          "product_ids": [
            "17084-1"
          ]
        }
      ],
      "title": "iommu/vt-d: Clear Present bit before tearing down PASID entry"
    }
  ]
}