FKIE_CVE-2026-64296
Vulnerability from fkie_nvd - Published: 2026-07-25 10:17 - Updated: 2026-07-30 15:00
Severity
Summary
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.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/exfat/dir.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "72a2589d82eb001c94b74bcfe6f9a599bd9bef60",
"status": "affected",
"version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
"versionType": "git"
},
{
"lessThan": "fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4",
"status": "affected",
"version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
"versionType": "git"
},
{
"lessThan": "cf85180b8a015029ee147694eaf4e0b3537e9432",
"status": "affected",
"version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
"versionType": "git"
},
{
"lessThan": "ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0",
"status": "affected",
"version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
"versionType": "git"
},
{
"lessThan": "727bf7783a2936ffd55c628dddfd69343e511dcf",
"status": "affected",
"version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
"versionType": "git"
},
{
"lessThan": "33c0b96d7e1672be1de0053786637ea46fb81507",
"status": "affected",
"version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
"versionType": "git"
},
{
"lessThan": "c8e041c68c0bbb73aa62371ee63947bb6949d8b2",
"status": "affected",
"version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
"versionType": "git"
},
{
"lessThan": "3a1230e7b043c62737b05a3e9275ca83a43ad20a",
"status": "affected",
"version": "ca06197382bde0a3bc20215595d1c9ce20c6e341",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/exfat/dir.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.7"
},
{
"lessThan": "5.7",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"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"
},
{
"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-rc1",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nexfat: bound uniname advance in exfat_find_dir_entry()\n\nIn exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the\noutput pointer by a fixed amount while the loop guard only tracks the\naccumulated name length:\n\n\tif (++order == 2)\n\t\tuniname = p_uniname-\u003ename;\n\telse\n\t\tuniname += EXFAT_FILE_NAME_LEN;\n\tlen = exfat_extract_uni_name(ep, entry_uniname);\n\tname_len += len;\n\tunichar = *(uniname+len);\n\t*(uniname+len) = 0x0;\n\nuniname grows by EXFAT_FILE_NAME_LEN (15) per name entry, but name_len\ngrows only by the actual extracted length, which is shorter when a name\nfragment contains an early NUL. The only guard is\n`name_len \u003e= MAX_NAME_LENGTH`, so a crafted directory with many short\nname fragments lets uniname run far past the\np_uniname-\u003ename[MAX_NAME_LENGTH + 3] buffer while name_len stays small,\ncausing an out-of-bounds read and write at *(uniname+len).\n\nThe sibling extractor exfat_get_uniname_from_ext_entry() already stops\non a short fragment (the lockstep `len != EXFAT_FILE_NAME_LEN` guard\nadded in commit d42334578eba (\"exfat: check if filename entries exceeds\nmax filename length\")); exfat_find_dir_entry() never got the\nequivalent. Track the per-entry write offset as a count and reject a\nfragment once the offset, or the offset plus the extracted length, would\nexceed MAX_NAME_LENGTH, before forming the output pointer."
}
],
"id": "CVE-2026-64296",
"lastModified": "2026-07-30T15:00:27.343",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-07-25T10:17:10.390",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/33c0b96d7e1672be1de0053786637ea46fb81507"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3a1230e7b043c62737b05a3e9275ca83a43ad20a"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/727bf7783a2936ffd55c628dddfd69343e511dcf"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/72a2589d82eb001c94b74bcfe6f9a599bd9bef60"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/c8e041c68c0bbb73aa62371ee63947bb6949d8b2"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/cf85180b8a015029ee147694eaf4e0b3537e9432"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
Loading…