CVE-2026-89840 (GCVE-0-2026-89840)

Vulnerability from cvelistv5 – Published: 2026-09-16 10:31 – Updated: 2026-09-21 13:15
VLAI
Title
f2fs: validate MOVE_RANGE destination size
Summary
In the Linux kernel, the following vulnerability has been resolved: f2fs: validate MOVE_RANGE destination size F2FS_IOC_MOVE_RANGE checks the source range, but not the destination end before updating i_size. A source hole can expose this: __clone_blkaddrs() skips NULL_ADDR entries and returns success, so the caller can still extend the destination inode with unchecked pos_out + len. Reject destination overflow and use inode_newsize_ok() before extending the destination inode.
Severity
7.1 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 4dd6f977fc778e5a0da604e5f8cb2f36d163d27b , < db13064669526494cd78ba3a4394063b740e940c (git)
Affected: 4dd6f977fc778e5a0da604e5f8cb2f36d163d27b , < dcae1eeda53149f219dd6af93b3083b7271c1c63 (git)
Affected: 4dd6f977fc778e5a0da604e5f8cb2f36d163d27b , < e533889fc26aea0cd83c90327063f272061dd820 (git)
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Linux Linux Affected: 4.8
Unaffected: 0 , < 4.8 (semver)
Unaffected: 6.18.53 , ≤ 6.18.* (semver)
Unaffected: 7.2.5 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/f2fs/file.c"
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          "vendor": "Linux",
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              "status": "affected",
              "version": "4dd6f977fc778e5a0da604e5f8cb2f36d163d27b",
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          "versions": [
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              "version": "0",
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              "versionType": "semver"
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: validate MOVE_RANGE destination size\n\nF2FS_IOC_MOVE_RANGE checks the source range, but not the destination end\nbefore updating i_size. A source hole can expose this: __clone_blkaddrs()\nskips NULL_ADDR entries and returns success, so the caller can still extend\nthe destination inode with unchecked pos_out + len.\n\nReject destination overflow and use inode_newsize_ok() before extending\nthe destination inode."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - F2FS_IOC_MOVE_RANGE is a local ioctl (f2fs_ioctl \u2192 f2fs_ioc_move_range \u2192 f2fs_move_file_range) on f2fs file descriptors. f2fs has no remap_file_range, so nfsd/ksmbd copy_file_range cannot reach this path.\nAC:L - The attacker fully controls pos_out and len and can ftruncate a sparse source so __clone_blkaddrs skips NULL_ADDR holes and returns success, making the unchecked destination i_size update deterministic with no race or uncontrollable layout.\nPR:L - f2fs_ioc_move_range has no capable() check; it only needs FMODE_READ|FMODE_WRITE on the source and FMODE_WRITE on the destination. Any unprivileged user with files on mounted f2fs (Android /data, embedded userdata) can trigger it.\nUI:N - The attacker opens their own files on an already-mounted f2fs volume and issues F2FS_IOC_MOVE_RANGE; no separate victim action such as mounting a filesystem or opening a crafted file is required.\nS:U - Impact is corruption of f2fs inode size metadata and subsequent filesystem/kernel state on the local host, a standard kernel compromise within the same security authority with no VM escape or IOMMU bypass.\nC:N - The bug writes an oversized or overflowed i_size; reads of the resulting sparse file return zeros or EOF (negative i_size makes pos \u003e= i_size), and lookups beyond max_file_blocks fail with -E2BIG, so there is no kernel-memory or cross-file disclosure primitive.\nI:H - Missing overflow and inode_newsize_ok() checks let the attacker set destination i_size past s_maxbytes or wrap size_t into a negative loff_t, persisting corrupt on-disk inode size and poisoning later paths (fallocate COLLAPSE nrpages, __exchange_data_block ALLOC_NODE) that trust i_size for block-tree updates.\nA:H - A poisoned i_size enables unbounded node-tree walks and block-exchange loops (SEEK_DATA/HOLE, fallocate COLLAPSE via DIV_ROUND_UP(i_size)), can hang the kernel or exhaust node space, and leaves durable filesystem corruption on shared f2fs userdata."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-21T13:15:08.455Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/db13064669526494cd78ba3a4394063b740e940c"
        },
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          "url": "https://git.kernel.org/stable/c/dcae1eeda53149f219dd6af93b3083b7271c1c63"
        },
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          "url": "https://git.kernel.org/stable/c/e533889fc26aea0cd83c90327063f272061dd820"
        }
      ],
      "title": "f2fs: validate MOVE_RANGE destination size",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89840",
    "datePublished": "2026-09-16T10:31:14.646Z",
    "dateReserved": "2026-09-11T19:38:34.769Z",
    "dateUpdated": "2026-09-21T13:15:08.455Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
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      "date": "2026-09-25",
      "epss": "0.00169",
      "percentile": "0.05503"
    },
    "microsoft_vex": {
      "current_release_date": "2026-09-24T02:37:12.000Z",
      "cve": "CVE-2026-89840",
      "id": "msrc_CVE-2026-89840",
      "initial_release_date": "2026-09-17T01:07:46.000Z",
      "product_status:known_affected": "3",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "f2fs: validate MOVE_RANGE destination size",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-89840.json",
      "version": "4"
    },
    "nvd": {
      "cve": {
        "affected": [
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                "product": "Linux",
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: validate MOVE_RANGE destination size\n\nF2FS_IOC_MOVE_RANGE checks the source range, but not the destination end\nbefore updating i_size. A source hole can expose this: __clone_blkaddrs()\nskips NULL_ADDR entries and returns success, so the caller can still extend\nthe destination inode with unchecked pos_out + len.\n\nReject destination overflow and use inode_newsize_ok() before extending\nthe destination inode."
          }
        ],
        "id": "CVE-2026-89840",
        "lastModified": "2026-09-21T14:17:27.507",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
                "availabilityImpact": "HIGH",
                "baseScore": 7.1,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "NONE",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
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              "impactScore": 5.2,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-09-16T11:16:50.837",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
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