Vulnerability-Lookup

FKIE_CVE-2026-74439

Vulnerability from fkie_nvd - Published: 2026-08-15 06:22 - Updated: 2026-08-17 06:19

Severity

9.3 (Critical) - CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Summary

In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry device_pasid_table_teardown() zeroes the 128-bit scalable-mode context entry with context_clear_entry() while the Present bit is still set. This creates a window where the hardware can fetch a torn entry, with some fields already zeroed while Present is still set, leading to unpredictable behavior or spurious faults. The context-cache invalidation is issued only after the entry has been zeroed, and intel_pasid_free_table() then frees the PASID directory pages, so the IOMMU can keep walking a stale Present=1 entry that points at freed memory. While x86 provides strong write ordering, the compiler may reorder the two 64-bit writes to the entry, and the hardware fetch is not guaranteed to be atomic with respect to multiple CPU writes. Commit c1e4f1dccbe9d ("iommu/vt-d: Clear Present bit before tearing down context entry") fixed this exact pattern in domain_context_clear_one() and the copied-context path, but device_pasid_table_teardown() was not converted. Align it with the "Guidance to Software for Invalidations" in the VT-d spec, Section 6.5.3.3, using the same ownership handshake as the sibling fix: clear only the Present bit, flush it to the IOMMU, perform the context-cache invalidation, and only then zero the rest of the entry.

References

	URL	Tags
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/588718101e8449605f1c7e858fecb7cfa701cdab
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/7fd4077dc92b91b1b844333c0a06bb9e286db10a
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/e9e83bcfe37dc719182500dd823c03ab57d934f0
	416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/f46452c3df7a8d8a5addc0926e76ef19ea7da0a0

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/intel/pasid.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e9e83bcfe37dc719182500dd823c03ab57d934f0",
              "status": "affected",
              "version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
              "versionType": "git"
            },
            {
              "lessThan": "588718101e8449605f1c7e858fecb7cfa701cdab",
              "status": "affected",
              "version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
              "versionType": "git"
            },
            {
              "lessThan": "7fd4077dc92b91b1b844333c0a06bb9e286db10a",
              "status": "affected",
              "version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
              "versionType": "git"
            },
            {
              "lessThan": "f46452c3df7a8d8a5addc0926e76ef19ea7da0a0",
              "status": "affected",
              "version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "333fe86968482ca701c609af590003bcea450e8f",
              "versionType": "git"
            },
            {
              "lessThan": "6.9",
              "status": "affected",
              "version": "6.8.2",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/intel/pasid.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
              "lessThan": "6.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "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 scalable-mode context entry\n\ndevice_pasid_table_teardown() zeroes the 128-bit scalable-mode context\nentry with context_clear_entry() while the Present bit is still set. This\ncreates a window where the hardware can fetch a torn entry, with some\nfields already zeroed while Present is still set, leading to unpredictable\nbehavior or spurious faults. The context-cache invalidation is issued only\nafter the entry has been zeroed, and intel_pasid_free_table() then frees\nthe PASID directory pages, so the IOMMU can keep walking a stale Present=1\nentry that points at freed memory.\n\nWhile x86 provides strong write ordering, the compiler may reorder the two\n64-bit writes to the entry, and the hardware fetch is not guaranteed to be\natomic with respect to multiple CPU writes.\n\nCommit c1e4f1dccbe9d (\"iommu/vt-d: Clear Present bit before tearing down\ncontext entry\") fixed this exact pattern in domain_context_clear_one() and\nthe copied-context path, but device_pasid_table_teardown() was not\nconverted.\n\nAlign it with the \"Guidance to Software for Invalidations\" in the VT-d\nspec, Section 6.5.3.3, using the same ownership handshake as the sibling\nfix: clear only the Present bit, flush it to the IOMMU, perform the\ncontext-cache invalidation, and only then zero the rest of the entry."
    }
  ],
  "id": "CVE-2026-74439",
  "lastModified": "2026-08-17T06:19:39.613",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 9.3,
          "baseSeverity": "CRITICAL",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.5,
        "impactScore": 6.0,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-08-15T06:22:46.023",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/588718101e8449605f1c7e858fecb7cfa701cdab"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7fd4077dc92b91b1b844333c0a06bb9e286db10a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e9e83bcfe37dc719182500dd823c03ab57d934f0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f46452c3df7a8d8a5addc0926e76ef19ea7da0a0"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}

CVE-2026-74439 (GCVE-0-2026-74439)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:59 – Updated: 2026-08-17 05:47

Title

iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry

Summary

Severity

9.3 (Critical)


                        
                          CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Assigner

Linux mitre root

References

4 references

URL	Tags
https://git.kernel.org/stable/c/e9e83bcfe37dc7191…
https://git.kernel.org/stable/c/588718101e8449605…
https://git.kernel.org/stable/c/7fd4077dc92b91b1b…
https://git.kernel.org/stable/c/f46452c3df7a8d8a5…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 81e921fd321614c2ad8ac333b041aae1da7a1c6d , < e9e83bcfe37dc719182500dd823c03ab57d934f0 (git) Affected: 81e921fd321614c2ad8ac333b041aae1da7a1c6d , < 588718101e8449605f1c7e858fecb7cfa701cdab (git) Affected: 81e921fd321614c2ad8ac333b041aae1da7a1c6d , < 7fd4077dc92b91b1b844333c0a06bb9e286db10a (git) Affected: 81e921fd321614c2ad8ac333b041aae1da7a1c6d , < f46452c3df7a8d8a5addc0926e76ef19ea7da0a0 (git) Affected: 333fe86968482ca701c609af590003bcea450e8f (git) Affected: 6.8.2 , < 6.9 (semver)
Linux	Linux	Affected: 6.9 Unaffected: 0 , < 6.9 (semver) Unaffected: 6.12.97 , ≤ 6.12.* (semver) Unaffected: 6.18.40 , ≤ 6.18.* (semver) Unaffected: 7.1.5 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/intel/pasid.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e9e83bcfe37dc719182500dd823c03ab57d934f0",
              "status": "affected",
              "version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
              "versionType": "git"
            },
            {
              "lessThan": "588718101e8449605f1c7e858fecb7cfa701cdab",
              "status": "affected",
              "version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
              "versionType": "git"
            },
            {
              "lessThan": "7fd4077dc92b91b1b844333c0a06bb9e286db10a",
              "status": "affected",
              "version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
              "versionType": "git"
            },
            {
              "lessThan": "f46452c3df7a8d8a5addc0926e76ef19ea7da0a0",
              "status": "affected",
              "version": "81e921fd321614c2ad8ac333b041aae1da7a1c6d",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "333fe86968482ca701c609af590003bcea450e8f",
              "versionType": "git"
            },
            {
              "lessThan": "6.9",
              "status": "affected",
              "version": "6.8.2",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/intel/pasid.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
              "lessThan": "6.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.97",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.40",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "6.8.2",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu/vt-d: Clear Present bit before tearing down scalable-mode context entry\n\ndevice_pasid_table_teardown() zeroes the 128-bit scalable-mode context\nentry with context_clear_entry() while the Present bit is still set. This\ncreates a window where the hardware can fetch a torn entry, with some\nfields already zeroed while Present is still set, leading to unpredictable\nbehavior or spurious faults. The context-cache invalidation is issued only\nafter the entry has been zeroed, and intel_pasid_free_table() then frees\nthe PASID directory pages, so the IOMMU can keep walking a stale Present=1\nentry that points at freed memory.\n\nWhile x86 provides strong write ordering, the compiler may reorder the two\n64-bit writes to the entry, and the hardware fetch is not guaranteed to be\natomic with respect to multiple CPU writes.\n\nCommit c1e4f1dccbe9d (\"iommu/vt-d: Clear Present bit before tearing down\ncontext entry\") fixed this exact pattern in domain_context_clear_one() and\nthe copied-context path, but device_pasid_table_teardown() was not\nconverted.\n\nAlign it with the \"Guidance to Software for Invalidations\" in the VT-d\nspec, Section 6.5.3.3, using the same ownership handshake as the sibling\nfix: clear only the Present bit, flush it to the IOMMU, perform the\ncontext-cache invalidation, and only then zero the rest of the entry."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.3,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The flaw is in Intel VT-d scalable-mode PASID context teardown reached only via local kernel IOMMU device-release paths (intel_iommu_release_device \u2192 device_pasid_table_teardown), triggered by PCI hot-unplug, sysfs driver unbind, or iommu deinit\u2014not by any network-facing protocol.\nAC:L - This is a use-after-free where intel_pasid_free_table() frees PASID directory pages while the IOMMU may still cache a Present=1 context entry; an attacker controlling a PASID-capable device can keep DMA active and time bus removal/teardown to hit the stale-entry window reliably (AC:L per UAF guidance).\nPR:N - A malicious PASID-capable PCIe device can trigger the vulnerable intel_iommu_release_device teardown by physical hot-unplug (pci_stop_and_remove_bus_device) while sustaining DMA, requiring no authenticated host account or capability on the target system.\nUI:N - No victim interaction is required beyond the attacker\u0027s own device removal or driver-unbind orchestration; the vulnerable teardown executes automatically once the PCI/IOMMU release path runs.\nS:C - A stale or torn scalable-mode context entry breaks VT-d DMA isolation\u2014the IOMMU can translate device DMA against freed PASID table memory, crossing the device/host (or guest/host) IOMMU security boundary per kernel IOMMU bypass guidance.\nC:H - With the IOMMU walking freed PASID directory pages, a controlled device can DMA-read host physical memory outside its assigned domain, yielding arbitrary cross-boundary read disclosure (C:H; UAF enables attacker influence over translation contents).\nI:H - The same mistranslation gives the device an arbitrary DMA write primitive against host memory outside its domain, enabling data modification and potential control-flow hijack via memory corruption (standard UAF/IOMMU-bypass I:H guidance).\nA:H - The commit documents unpredictable behavior and spurious DMAR faults from torn Present entries; freed PASID tables under active IOMMU walks can fault-storm, hang, or panic the host\u2014any kernel crash/UAF qualifies as A:H."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:47:13.219Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e9e83bcfe37dc719182500dd823c03ab57d934f0"
        },
        {
          "url": "https://git.kernel.org/stable/c/588718101e8449605f1c7e858fecb7cfa701cdab"
        },
        {
          "url": "https://git.kernel.org/stable/c/7fd4077dc92b91b1b844333c0a06bb9e286db10a"
        },
        {
          "url": "https://git.kernel.org/stable/c/f46452c3df7a8d8a5addc0926e76ef19ea7da0a0"
        }
      ],
      "title": "iommu/vt-d: Clear Present bit before tearing down scalable-mode context entry",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74439",
    "datePublished": "2026-08-15T05:59:36.655Z",
    "dateReserved": "2026-08-15T05:44:03.897Z",
    "dateUpdated": "2026-08-17T05:47:13.219Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

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FKIE_CVE-2026-74439

CVE-2026-74439 (GCVE-0-2026-74439)

Tags

Sightings

Nomenclature