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exfat: bound uniname advance in exfat_find_dir_entry()

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: exfat: bound uniname advance in exfat_find_dir_entry() In exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the output pointer by a fixed amount while the loop guard only tracks the accumulated name length: if (++order == 2) uniname = p_uniname->name; else uniname += EXFAT_FILE_NAME_LEN; len = exfat_extract_uni_name(ep, entry_uniname); name_len += len; unichar = *(uniname+len); *(uniname+len) = 0x0; uniname grows by EXFAT_FILE_NAME_LEN (15) per name entry, but name_len grows only by the actual extracted length, which is shorter when a name fragment contains an early NUL. The only guard is `name_len >= MAX_NAME_LENGTH`, so a crafted directory with many short name fragments lets uniname run far past the p_uniname->name[MAX_NAME_LENGTH + 3] buffer while name_len stays small, causing an out-of-bounds read and write at *(uniname+len). The sibling extractor exfat_get_uniname_from_ext_entry() already stops on a short fragment (the lockstep `len != EXFAT_FILE_NAME_LEN` guard added in commit d42334578eba ("exfat: check if filename entries exceeds max filename length")); exfat_find_dir_entry() never got the equivalent. Track the per-entry write offset as a count and reject a fragment once the offset, or the offset plus the extracted length, would exceed MAX_NAME_LENGTH, before forming the output pointer.

Announced Source revision 1
Original source ↗

CVE-2026-64296

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-64296

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
        "lessThan": "72a2589d82eb001c94b74bcfe6f9a599bd9bef60",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
        "lessThan": "fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
        "lessThan": "cf85180b8a015029ee147694eaf4e0b3537e9432",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
        "lessThan": "ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
        "lessThan": "727bf7783a2936ffd55c628dddfd69343e511dcf",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
        "lessThan": "33c0b96d7e1672be1de0053786637ea46fb81507",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
        "lessThan": "c8e041c68c0bbb73aa62371ee63947bb6949d8b2",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
        "lessThan": "3a1230e7b043c62737b05a3e9275ca83a43ad20a",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "fs/exfat/dir.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.7"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.7",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.261",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.212",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.178",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.145",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.96",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.39",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.1.4",
        "versionType": "semver",
        "lessThanOrEqual": "7.1.*"
      },
      {
        "status": "unaffected",
        "version": "7.2",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "fs/exfat/dir.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-64296

Source reference: /cveMetadata/cveId

Publisher severity

high

Source reference: /containers/cna/metrics

Event
#41001 · Revision 1
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Publisher date
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