CVE-2026-64152 (GCVE-0-2026-64152)
Vulnerability from cvelistv5
Published
2026-07-19 15:40
Modified
2026-08-05 12:39
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: iommu: Handle unmap error when iommu_debug is enabled Sashiko noticed a latent bug where the map error flow called iommu_unmap() which calls iommu_debug_unmap_begin()/iommu_debug_unmap_end() however since this is an error path the map flow never actually established the original iommu_debug_map() it will malfunction. Lift the unmap error handling into iommu_map_nosync() and reorder it so the trace_map()/iommu_debug_map() records the partial mapping and then immediately unmaps it. This avoid creating the unbalanced tracking and provides saner tracing instead of a unmap unmatched to any map.
References
Impacted products
Vendor Product Version
Linux Linux Version: ccc21213f013834b484cdcc738e282f963fcfc97
Version: ccc21213f013834b484cdcc738e282f963fcfc97
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/iommu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "0cd028806efc148a75d4acf711d21db335a89661",
              "status": "affected",
              "version": "ccc21213f013834b484cdcc738e282f963fcfc97",
              "versionType": "git"
            },
            {
              "lessThan": "0735c54804c709d1b292f3b6947cfb560b2ce552",
              "status": "affected",
              "version": "ccc21213f013834b484cdcc738e282f963fcfc97",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/iommu/iommu.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "lessThan": "7.0",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0.11",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1",
                  "versionStartIncluding": "7.0",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\niommu: Handle unmap error when iommu_debug is enabled\n\nSashiko noticed a latent bug where the map error flow called iommu_unmap()\nwhich calls iommu_debug_unmap_begin()/iommu_debug_unmap_end() however\nsince this is an error path the map flow never actually established the\noriginal iommu_debug_map() it will malfunction.\n\nLift the unmap error handling into iommu_map_nosync() and reorder it so\nthe trace_map()/iommu_debug_map() records the partial mapping and then\nimmediately unmaps it. This avoid creating the unbalanced tracking and\nprovides saner tracing instead of a unmap unmatched to any map."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerable code is reached only through local kernel IOMMU APIs invoked from userspace ioctl paths such as IOMMUFD IOAS mapping (/dev/iommu) and VFIO DMA mapping (/dev/vfio/vfio), not from any network packet handler.\nAC:H - Exploitation requires CONFIG_IOMMU_DEBUG_PAGEALLOC plus the iommu.debug_pagealloc=1 boot parameter (both admin-controlled debug options absent from production kernels) and a partial IOMMU map failure, conditions the attacker cannot establish unilaterally.\nPR:L - Triggering iommu_map() requires only local userspace access to IOMMUFD or VFIO interfaces (e.g., /dev/vfio/vfio at mode 0666), which an unprivileged local user or cloud VM tenant with assigned passthrough devices can obtain without host root.\nUI:N - No victim interaction is required; the attacker triggers the bug directly through IOMMU map ioctl operations that fail partway through.\nS:C - The bug corrupts IOMMU page-tracking metadata used to enforce the DMA/IOMMU security boundary, and a VM tenant with VFIO passthrough can trigger it in the host kernel, crossing the guest-to-host security authority.\nC:H - Unbalanced debug refcount decrements corrupt page_ext IOMMU tracking state, which can suppress detection of pages still mapped for DMA and thereby permit device reads of host physical memory that should be isolated.\nI:H - Corrupted IOMMU debug tracking is memory corruption in kernel metadata that can mask stale DMA mappings, enabling a device to write host memory across the IOMMU boundary; WARN_ON underflow paths also demonstrate uncontrolled kernel state corruption.\nA:H - The bug triggers WARN_ON on atomic refcount underflow during unmap_begin/dec_page, which can cause kernel oops or panic (especially with panic_on_warn), constituting high availability impact."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:39:46.961Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0cd028806efc148a75d4acf711d21db335a89661"
        },
        {
          "url": "https://git.kernel.org/stable/c/0735c54804c709d1b292f3b6947cfb560b2ce552"
        }
      ],
      "title": "iommu: Handle unmap error when iommu_debug is enabled",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64152",
    "datePublished": "2026-07-19T15:40:41.354Z",
    "dateReserved": "2026-07-19T07:54:57.037Z",
    "dateUpdated": "2026-08-05T12:39:46.961Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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