CVE-2026-64323 (GCVE-0-2026-64323)
Vulnerability from cvelistv5
Published
2026-07-25 08:49
Modified
2026-08-17 04:53
Severity ?
7.1 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: udf: validate VAT header length against the VAT inode size udf_load_vat() takes the virtual partition's start offset straight from the on-disk VAT 2.0 header without checking it against the VAT inode size: map->s_type_specific.s_virtual.s_start_offset = le16_to_cpu(vat20->lengthHeader); map->s_type_specific.s_virtual.s_num_entries = (sbi->s_vat_inode->i_size - map->s_type_specific.s_virtual.s_start_offset) >> 2; lengthHeader is a fully attacker-controlled 16-bit value. If it exceeds the VAT inode size, the s_num_entries subtraction underflows to a huge count, which defeats the "block > s_num_entries" bound in udf_get_pblock_virt15(); and on the ICB-inline path that function reads ((__le32 *)(iinfo->i_data + s_start_offset))[block] so a large s_start_offset indexes past the inode's in-ICB data. Mounting a crafted UDF image with a virtual (VAT) partition then triggers an out-of-bounds read. Reject a VAT whose header length does not leave room for at least one entry within the VAT inode.
References
Impacted products
Vendor Product Version
Linux Linux Version: fa5e08156335d0687c85b4e724db9448fb166601
Version: fa5e08156335d0687c85b4e724db9448fb166601
Version: fa5e08156335d0687c85b4e724db9448fb166601
Version: fa5e08156335d0687c85b4e724db9448fb166601
Version: fa5e08156335d0687c85b4e724db9448fb166601
Version: fa5e08156335d0687c85b4e724db9448fb166601
Version: fa5e08156335d0687c85b4e724db9448fb166601
Version: fa5e08156335d0687c85b4e724db9448fb166601
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/udf/super.c"
          ],
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          "vendor": "Linux",
          "versions": [
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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": [
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              "version": "2.6.26"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "5.10.261",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.212",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.178",
              "versionType": "semver"
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              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.96",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.39",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.261",
                  "versionStartIncluding": "2.6.26",
                  "vulnerable": true
                },
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                  "versionEndExcluding": "5.15.212",
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                  "vulnerable": true
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                  "versionEndExcluding": "6.6.145",
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                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.96",
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                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "2.6.26",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nudf: validate VAT header length against the VAT inode size\n\nudf_load_vat() takes the virtual partition\u0027s start offset straight from\nthe on-disk VAT 2.0 header without checking it against the VAT inode\nsize:\n\n\tmap-\u003es_type_specific.s_virtual.s_start_offset =\n\t\tle16_to_cpu(vat20-\u003elengthHeader);\n\tmap-\u003es_type_specific.s_virtual.s_num_entries =\n\t\t(sbi-\u003es_vat_inode-\u003ei_size -\n\t\t\tmap-\u003es_type_specific.s_virtual.s_start_offset) \u003e\u003e 2;\n\nlengthHeader is a fully attacker-controlled 16-bit value.  If it exceeds\nthe VAT inode size, the s_num_entries subtraction underflows to a huge\ncount, which defeats the \"block \u003e s_num_entries\" bound in\nudf_get_pblock_virt15(); and on the ICB-inline path that function reads\n\n\t((__le32 *)(iinfo-\u003ei_data + s_start_offset))[block]\n\nso a large s_start_offset indexes past the inode\u0027s in-ICB data.  Mounting\na crafted UDF image with a virtual (VAT) partition then triggers an\nout-of-bounds read.\n\nReject a VAT whose header length does not leave room for at least one\nentry within the VAT inode."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerable parser is reached by mounting a crafted local UDF image or removable volume; no network-facing protocol reaches it.\nAC:L - The VAT type, inline allocation, header length, and virtual block index are attacker-controlled on disk, with no race or uncontrollable condition required.\nPR:L - Although direct mounting requires init-namespace CAP_SYS_ADMIN, common UDisks/polkit deployments let an active unprivileged local user create a loop device and request the mount.\nUI:N - In the low-privilege UDisks scenario, the attacker can initiate the mount and trigger VAT resolution without another user\u0027s action.\nS:U - The vulnerable UDF parser and affected kernel resources remain within the host kernel\u0027s security authority.\nC:H - The underflow permits repeatable 32-bit reads at attacker-selected offsets potentially many gigabytes beyond the VAT buffer, enabling disclosure of kernel memory.\nI:N - The primitive only reads a mapping value, and virtual UDF partitions are forcibly read-only; no kernel-memory write primitive results.\nA:H - A sufficiently large attacker-selected index can fault in kernel context and cause an oops or panic, enabling repeatable system-wide denial of service."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:53:25.005Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/0ad2d09a8d66fa8dc6f9b70d660b5fb4478ea934"
        },
        {
          "url": "https://git.kernel.org/stable/c/883962731420ec271ed8c1cd76524f4b17faa982"
        },
        {
          "url": "https://git.kernel.org/stable/c/2900e02a0dd4fc30ac9840e7ce4ca0b041ab0d63"
        },
        {
          "url": "https://git.kernel.org/stable/c/bb0d384c1f42a5b7ace0bd88fee80b9bb1d49acb"
        },
        {
          "url": "https://git.kernel.org/stable/c/55287a3555ff0515b3aff181d2c08c0462a41709"
        },
        {
          "url": "https://git.kernel.org/stable/c/e610fb113cdfa8bf4247c9bf4f2337b81ad4ddad"
        },
        {
          "url": "https://git.kernel.org/stable/c/74580fdf022909e184223cacc364feb826982d96"
        },
        {
          "url": "https://git.kernel.org/stable/c/d8202786b3d75125c84ebc4de6d946f92fde0ee8"
        }
      ],
      "title": "udf: validate VAT header length against the VAT inode size",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64323",
    "datePublished": "2026-07-25T08:49:51.097Z",
    "dateReserved": "2026-07-19T15:36:31.780Z",
    "dateUpdated": "2026-08-17T04:53:25.005Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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