CVE-2026-45892
Full vulnerability record from the local CVENow database.
Description
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. 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 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. 0 A B N [UUUUUUUUUUUU] on-disk extent [UUUUUUUUUUUU] extent status tree [--DDDDDDDDZZ] Z: zeroed data 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. 0 A B N [UUWWWWWWWWWW] on-disk extent W: written extent [UUUUUUUUUUUU] extent status tree [--DDDDDDDDZZ] 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. 0 A B N [UUWWWWWWWWWW] on-disk extent W: written extent [UUWWWWWWWWUU] extent status tree [--DDDDDDDDZZ] Fix this issue by always cached extent status entry after zeroing out the second part.
View original CVE JSON
{
"id": "CVE-2026-45892",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-05-27T14:17:03.353",
"lastModified": "2026-11-06T16:18:49.813",
"vulnStatus": "Analyzed",
"cveTags": [],
"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."
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"fs/ext4/extents.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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"versionType": "git",
"status": "affected"
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{
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"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"fs/ext4/extents.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "6.1.167",
"lessThan": "6.1.168",
"versionType": "semver",
"status": "affected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV31": [
{
"source": "[email protected]",
"type": "Primary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 1.8,
"impactScore": 3.6
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-11-06T15:43:46.849985Z",
"id": "CVE-2026-45892",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
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{
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}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
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},
"weaknesses": [
{
"source": "[email protected]",
"type": "Primary",
"description": [
{
"lang": "en",
"value": "NVD-CWE-noinfo"
}
]
}
],
"configurations": [
{
"nodes": [
{
"operator": "OR",
"negate": false,
"cpeMatch": [
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"criteria": "cpe:2.3:o:linux:linux_kernel:6.1.167:*:*:*:*:*:*:*",
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