CVE-2023-53473 (GCVE-0-2023-53473)
Vulnerability from cvelistv5
Published
2025-10-01 11:42
Modified
2026-08-05 09:14
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: improve error handling from ext4_dirhash() The ext4_dirhash() will *almost* never fail, especially when the hash tree feature was first introduced. However, with the addition of support of encrypted, casefolded file names, that function can most certainly fail today. So make sure the callers of ext4_dirhash() properly check for failures, and reflect the errors back up to their callers.
References
Impacted products
Vendor Product Version
Linux Linux Version: b886ee3e778ec2ad43e276fd378ab492cf6819b7
Version: b886ee3e778ec2ad43e276fd378ab492cf6819b7
Version: b886ee3e778ec2ad43e276fd378ab492cf6819b7
Version: b886ee3e778ec2ad43e276fd378ab492cf6819b7
Version: b886ee3e778ec2ad43e276fd378ab492cf6819b7
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ext4/hash.c",
            "fs/ext4/namei.c"
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          "product": "Linux",
          "programFiles": [
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            "fs/ext4/namei.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.2"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "5.15.112",
              "versionType": "semver"
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              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.29",
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              "lessThanOrEqual": "6.2.*",
              "status": "unaffected",
              "version": "6.2.16",
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              "lessThanOrEqual": "6.3.*",
              "status": "unaffected",
              "version": "6.3.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.4",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.112",
                  "versionStartIncluding": "5.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.29",
                  "versionStartIncluding": "5.2",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
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                {
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              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: improve error handling from ext4_dirhash()\n\nThe ext4_dirhash() will *almost* never fail, especially when the hash\ntree feature was first introduced.  However, with the addition of\nsupport of encrypted, casefolded file names, that function can most\ncertainly fail today.\n\nSo make sure the callers of ext4_dirhash() properly check for\nfailures, and reflect the errors back up to their callers."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The vulnerability is triggered entirely through local syscalls (`getdents64()`/`lseek()` on a directory of a mounted ext4 filesystem, or `creat()`/`rename()` driving `do_split`). No network protocol handler is involved.\nAC:L - The syzbot reproducer is fully deterministic \u2014 a superblock with `s_def_hash_version = DX_HASH_SIPHASH` plus a single `getdents64()` makes `ext4fs_dirhash()` fail on every directory entry, with no race or memory-layout condition outside the attacker\u0027s control.\nPR:L - An ordinary unprivileged local user performs the whole attack \u2014 reading the directory and recovering the leaked stack bytes via `telldir()`; the mounted crafted image is obtained through removable-media automount (udisks2 on desktops/kiosks), and the `-ENOMEM` variant needs no crafted image at all on a normal casefolded volume.\nUI:N - No second party needs to act \u2014 the same attacker supplies the medium and issues the syscalls, and on a legitimately mounted casefolded filesystem the allocation-failure path triggers with no user action whatsoever.\nS:U - The uninitialized read, the disclosure, and the metadata corruption all stay within the kernel\u0027s own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - Uninitialized kernel stack memory is handed straight to userspace as the readdir file position (`hash2pos()` \u2192 `f_pos` \u2192 `telldir`), repeatably and from a fixed stack slot the attacker can pre-seed with earlier syscalls, yielding a general kernel-stack read primitive that leaks pointers and defeats KASLR.\nI:H - Garbage/zero hash values are propagated into on-disk metadata \u2014 `ext4_insert_dentry` stores them in dirents, `make_indexed_dir`/`dx_insert_block` write them into htree nodes, and `dx_make_map`+`do_split` relocate directory entries based on stale hashes \u2014 corrupting the directory index of a mounted filesystem.\nA:H - The resulting index inconsistency drives `EXT4_ERROR_INODE`/`ext4_error`, forcing a remount-read-only on the default `errors=remount-ro` and a full kernel panic under `errors=panic`, while the garbage rbtree hashes can make `ext4_dx_readdir` return inconsistent results or fail to converge."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T09:14:14.651Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/b2531936118deb3f479c4fa1bcd787b74b8faa6a"
        },
        {
          "url": "https://git.kernel.org/stable/c/f68876aeef96ef8b708ab10b9cb47ce0a5adb424"
        },
        {
          "url": "https://git.kernel.org/stable/c/70d579aefa652a06af97e013e3fbbabbe5a43553"
        },
        {
          "url": "https://git.kernel.org/stable/c/c1fae027da61fe8e7eb99f7244297e81bc0f1e43"
        },
        {
          "url": "https://git.kernel.org/stable/c/4b3cb1d108bfc2aebb0d7c8a52261a53cf7f5786"
        }
      ],
      "title": "ext4: improve error handling from ext4_dirhash()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2023-53473",
    "datePublished": "2025-10-01T11:42:42.875Z",
    "dateReserved": "2025-10-01T11:39:39.401Z",
    "dateUpdated": "2026-08-05T09:14:14.651Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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