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CVE-2026-89640

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: cifs: fix loff_t underflow in cifs_remap_file_range() when len == 0 With len == 0 (clone to EOF), the effective length is computed as: len = src_inode->i_size - off; If off > i_size, this is a negative loff_t, corrupting the ByteCount in the FSCTL_DUPLICATE_EXTENTS_TO_FILE request and inverting the range in filemap_write_and_wait_range(). The existing off >= i_size check fires only after the ioctl has already been sent. Snapshot i_size_read() once for both the bounds check and the length calculation, eliminating the TOCTOU and 32-bit torn-read risk. Reject off > src_size with -EINVAL. Treat off == src_size as a no-op, consistent with __generic_remap_file_range_prep().

Severity
HIGH
CVSS score
7.1 (v3.1)
Vulnerability status
Received
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-09-11 20:19:49.733000
Last modified
2026-10-30 13:20:23.577000
View original CVE JSON 
{
  "id": "CVE-2026-89640",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-09-11T20:19:49.733",
  "lastModified": "2026-10-30T13:20:23.577",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: fix loff_t underflow in cifs_remap_file_range() when len == 0\n\nWith len == 0 (clone to EOF), the effective length is computed as:\n\n    len = src_inode->i_size - off;\n\nIf off > i_size, this is a negative loff_t, corrupting the ByteCount\nin the FSCTL_DUPLICATE_EXTENTS_TO_FILE request and inverting the range\nin filemap_write_and_wait_range().  The existing off >= i_size check\nfires only after the ioctl has already been sent.\n\nSnapshot i_size_read() once for both the bounds check and the length\ncalculation, eliminating the TOCTOU and 32-bit torn-read risk.  Reject\noff > src_size with -EINVAL.  Treat off == src_size as a no-op,\nconsistent with __generic_remap_file_range_prep()."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "fs/smb/client/cifsfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "04b38d601239b4d9be641b412cf4b7456a041c67",
              "lessThan": "2c6eede83b3de1268db92c7e49741761c954aa26",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "04b38d601239b4d9be641b412cf4b7456a041c67",
              "lessThan": "ce813e5eebf46851e872ce59bdc34dc5dd4e29a4",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "04b38d601239b4d9be641b412cf4b7456a041c67",
              "lessThan": "f3d1ae1e6bc4a9f559185b6e7bd2b6375ec2fdd4",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "04b38d601239b4d9be641b412cf4b7456a041c67",
              "lessThan": "7f62817fe049b0f3652518c1ba72631ec1e0a322",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "04b38d601239b4d9be641b412cf4b7456a041c67",
              "lessThan": "b098f5e5858797827666e6cd73033f52fc39b5f6",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "04b38d601239b4d9be641b412cf4b7456a041c67",
              "lessThan": "c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "04b38d601239b4d9be641b412cf4b7456a041c67",
              "lessThan": "b057ca17b656345d04669cb87f2aff9b31d873db",
              "versionType": "git",
              "status": "affected"
            },
            {
              "version": "04b38d601239b4d9be641b412cf4b7456a041c67",
              "lessThan": "6c322f5cf7476ded7a9a20f7be72462065a03c68",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "fs/smb/client/cifsfs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "4.5",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "4.5",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.10.273",
              "lessThanOrEqual": "5.10.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "5.15.224",
              "lessThanOrEqual": "5.15.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.188",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.157",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.109",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.50",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2.4",
              "lessThanOrEqual": "7.2.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.3",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV31": [
      {
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "attackVector": "LOCAL",
          "attackComplexity": "LOW",
          "privilegesRequired": "LOW",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.2
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-10-16T19:24:54.678656Z",
          "id": "CVE-2026-89640",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/2c6eede83b3de1268db92c7e49741761c954aa26",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/6c322f5cf7476ded7a9a20f7be72462065a03c68",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/7f62817fe049b0f3652518c1ba72631ec1e0a322",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b057ca17b656345d04669cb87f2aff9b31d873db",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/b098f5e5858797827666e6cd73033f52fc39b5f6",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/c2a0dcb5a7a1516aa6eb6d5cedca6a8e76527028",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/ce813e5eebf46851e872ce59bdc34dc5dd4e29a4",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/f3d1ae1e6bc4a9f559185b6e7bd2b6375ec2fdd4",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}