CVE-2026-45892
Estado: AnalizadaMedia (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
ext4: drop extent cache after doing PARTIAL_VALID1 zeroout
When splitting an unwritten extent in the middle and converting it to initialized in ext4_split_extent() with the EXT4_EXT_MAY_ZEROOUT and EXT4_EXT_DATA_VALID2 flags set, it could leave a stale unwritten extent.
Assume we have an unwritten file and buffered write in the middle of it without dioread_nolock enabled, it will allocate blocks as written extent.
ext4_split_extent() first try to split this extent at B with EXT4_EXT_DATA_PARTIAL_VALID1 and EXT4_EXT_MAY_ZEROOUT flag set, but ext4_split_extent_at() failed to split this extent due to temporary lack of space. It zeroout B to N and leave the entire extent as unwritten.
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ext4_split_extent() then try to split this extent at A with EXT4_EXT_DATA_VALID2 flag set. This time, it split successfully and leave an written extent from A to N.
Finally ext4_map_create_blocks() only insert extent A to B to the extent status tree, and leave an stale unwritten extent in the status tree.
Fix this issue by always cached extent status entry after zeroing out the second part.
Detalles técnicos trazas, registros y código del informe original
0 A B N
[UUUUUUUUUUUU] on-disk extent U: unwritten extent
[UUUUUUUUUUUU] extent status tree
[--DDDDDDDD--] D: valid data
|<- ->| ----> this range needs to be initialized
0 A B N
[UUUUUUUUUUUU] on-disk extent
[UUUUUUUUUUUU] extent status tree
[--DDDDDDDDZZ] Z: zeroed data
0 A B N
[UUWWWWWWWWWW] on-disk extent W: written extent
[UUUUUUUUUUUU] extent status tree
[--DDDDDDDDZZ]
0 A B N
[UUWWWWWWWWWW] on-disk extent W: written extent
[UUWWWWWWWWUU] extent status tree
[--DDDDDDDDZZ]CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Puntuación base: 5.5
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.16%
- Percentil entre todas las CVEs puntuadas: 5
- Fecha de la puntuación: 5/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
CWE
- NVD-CWE-noinfo
Referencias
- https://git.kernel.org/stable/c/28db4bfc6f82fd20e2aadb7fc162244109a4eb31
- https://git.kernel.org/stable/c/6d882ea3b0931b43530d44149b79fcd4ffc13030
- https://git.kernel.org/stable/c/a1b962a821e7a52d48212ae269b45808b4411267
- https://git.kernel.org/stable/c/c2ee51d684adca7645e4aa74adca13f6750390bc
- https://git.kernel.org/stable/c/d8ee559fccdef713f058cfe5f2c03dc9b18be3b1
- https://git.kernel.org/stable/c/f0931a5c17005a0c4fc35bd1a001245effc3354b
JSON original (NVD)
Mostrar
{
"id": "CVE-2026-45892",
"cveTags": [],
"metrics": {
"cvssMetricV31": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"cvssData": {
"scope": "UNCHANGED",
"version": "3.1",
"baseScore": 5.5,
"attackVector": "LOCAL",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "LOW",
"confidentialityImpact": "NONE"
},
"impactScore": 3.6,
"exploitabilityScore": 1.8
}
]
},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
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"vendor": "Linux",
"product": "Linux",
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"versionType": "git"
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{
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{
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{
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"versionType": "git"
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{
"status": "affected",
"version": "7015fcf473796e1d2d876f241bd9e0c36f3d4eef",
"lessThan": "a1b962a821e7a52d48212ae269b45808b4411267",
"versionType": "git"
},
{
"status": "affected",
"version": "1bf6974822d1dba86cf11b5f05498581cf3488a2",
"lessThan": "6d882ea3b0931b43530d44149b79fcd4ffc13030",
"versionType": "git"
}
],
"programFiles": [
"fs/ext4/extents.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.1.167",
"lessThan": "6.1.168",
"versionType": "semver"
}
],
"programFiles": [
"fs/ext4/extents.c"
],
"defaultStatus": "unaffected"
}
]
}
],
"published": "2026-05-27T14:17:03.353",
"references": [
{
"url": "https://git.kernel.org/stable/c/28db4bfc6f82fd20e2aadb7fc162244109a4eb31",
"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/6d882ea3b0931b43530d44149b79fcd4ffc13030",
"tags": [
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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"tags": [
"Patch"
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Analyzed",
"weaknesses": [
{
"type": "Primary",
"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
"value": "NVD-CWE-noinfo"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: drop extent cache after doing PARTIAL_VALID1 zeroout\n\nWhen splitting an unwritten extent in the middle and converting it to\ninitialized in ext4_split_extent() with the EXT4_EXT_MAY_ZEROOUT and\nEXT4_EXT_DATA_VALID2 flags set, it could leave a stale unwritten extent.\n\nAssume we have an unwritten file and buffered write in the middle of it\nwithout dioread_nolock enabled, it will allocate blocks as written\nextent.\n\n 0 A B N\n [UUUUUUUUUUUU] on-disk extent U: unwritten extent\n [UUUUUUUUUUUU] extent status tree\n [--DDDDDDDD--] D: valid data\n |<- ->| ----> this range needs to be initialized\n\next4_split_extent() first try to split this extent at B with\nEXT4_EXT_DATA_PARTIAL_VALID1 and EXT4_EXT_MAY_ZEROOUT flag set, but\next4_split_extent_at() failed to split this extent due to temporary lack\nof space. It zeroout B to N and leave the entire extent as unwritten.\n\n 0 A B N\n [UUUUUUUUUUUU] on-disk extent\n [UUUUUUUUUUUU] extent status tree\n [--DDDDDDDDZZ] Z: zeroed data\n\next4_split_extent() then try to split this extent at A with\nEXT4_EXT_DATA_VALID2 flag set. This time, it split successfully and\nleave an written extent from A to N.\n\n 0 A B N\n [UUWWWWWWWWWW] on-disk extent W: written extent\n [UUUUUUUUUUUU] extent status tree\n [--DDDDDDDDZZ]\n\nFinally ext4_map_create_blocks() only insert extent A to B to the extent\nstatus tree, and leave an stale unwritten extent in the status tree.\n\n 0 A B N\n [UUWWWWWWWWWW] on-disk extent W: written extent\n [UUWWWWWWWWUU] extent status tree\n [--DDDDDDDDZZ]\n\nFix this issue by always cached extent status entry after zeroing out\nthe second part."
}
],
"lastModified": "2026-06-25T21:11:06.653",
"configurations": [
{
"nodes": [
{
"negate": false,
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:6.1.167:*:*:*:*:*:*:*",
"vulnerable": true,
"matchCriteriaId": "B898A4FB-4E74-40F7-B523-B71FFB681B6D"
}
],
"operator": "OR"
}
]
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}