CVE-2026-45851 (GCVE-0-2026-45851)
Vulnerability from cvelistv5
Published
2026-05-27 12:15
Modified
2026-05-27 12:15
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: efi: Fix reservation of unaccepted memory table The reserve_unaccepted() function incorrectly calculates the size of the memblock reservation for the unaccepted memory table. It aligns the size of the table, but fails to account for cases where the table's starting physical address (efi.unaccepted) is not page-aligned. If the table starts at an offset within a page and its end crosses into a subsequent page that the aligned size does not cover, the end of the table will not be reserved. This can lead to the table being overwritten or inaccessible, causing a kernel panic in accept_memory(). This issue was observed when starting Intel TDX VMs with specific memory sizes (e.g., > 64GB). Fix this by calculating the end address first (including the unaligned start) and then aligning it up, ensuring the entire range is covered by the reservation.
References
Impacted products
Vendor Product Version
Linux Linux Version: 8dbe33956d96c9d066ef15ca933ede30748198b2
Version: 8dbe33956d96c9d066ef15ca933ede30748198b2
Version: 8dbe33956d96c9d066ef15ca933ede30748198b2
Version: 8dbe33956d96c9d066ef15ca933ede30748198b2
Version: 8dbe33956d96c9d066ef15ca933ede30748198b2
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/firmware/efi/efi.c"
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        },
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          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.6"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "version": "6.12.75",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.18.14",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.128",
                  "versionStartIncluding": "6.6",
                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nefi: Fix reservation of unaccepted memory table\n\nThe reserve_unaccepted() function incorrectly calculates the size of the\nmemblock reservation for the unaccepted memory table. It aligns the\nsize of the table, but fails to account for cases where the table\u0027s\nstarting physical address (efi.unaccepted) is not page-aligned.\n\nIf the table starts at an offset within a page and its end crosses into\na subsequent page that the aligned size does not cover, the end of the\ntable will not be reserved. This can lead to the table being overwritten\nor inaccessible, causing a kernel panic in accept_memory().\n\nThis issue was observed when starting Intel TDX VMs with specific memory\nsizes (e.g., \u003e 64GB).\n\nFix this by calculating the end address first (including the unaligned\nstart) and then aligning it up, ensuring the entire range is covered\nby the reservation."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-27T12:15:23.221Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/b7bc182ec1846be437351e44164089d988f9d0dd"
        },
        {
          "url": "https://git.kernel.org/stable/c/ba6b6f1502fa55621d1db23f253d54322bdbe4e0"
        },
        {
          "url": "https://git.kernel.org/stable/c/9b18bf59977f5c5bc3b11b210520f62500a7adf3"
        },
        {
          "url": "https://git.kernel.org/stable/c/e649b5916725c68f44ebf45fb396df563c5dbaf2"
        },
        {
          "url": "https://git.kernel.org/stable/c/0862438c90487e79822d5647f854977d50381505"
        }
      ],
      "title": "efi: Fix reservation of unaccepted memory table",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-45851",
    "datePublished": "2026-05-27T12:15:23.221Z",
    "dateReserved": "2026-05-13T15:03:33.079Z",
    "dateUpdated": "2026-05-27T12:15:23.221Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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