CVE-2026-43067 (GCVE-0-2026-43067)
Vulnerability from cvelistv5
Published
2026-05-05 15:23
Modified
2026-10-19 19:06
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
ext4: handle wraparound when searching for blocks for indirect mapped blocks
Commit 4865c768b563 ("ext4: always allocate blocks only from groups
inode can use") restricts what blocks will be allocated for indirect
block based files to block numbers that fit within 32-bit block
numbers.
However, when using a review bot running on the latest Gemini LLM to
check this commit when backporting into an LTS based kernel, it raised
this concern:
If ac->ac_g_ex.fe_group is >= ngroups (for instance, if the goal
group was populated via stream allocation from s_mb_last_groups),
then start will be >= ngroups.
Does this allow allocating blocks beyond the 32-bit limit for
indirect block mapped files? The commit message mentions that
ext4_mb_scan_groups_linear() takes care to not select unsupported
groups. However, its loop uses group = *start, and the very first
iteration will call ext4_mb_scan_group() with this unsupported
group because next_linear_group() is only called at the end of the
iteration.
After reviewing the code paths involved and considering the LLM
review, I determined that this can happen when there is a file system
where some files/directories are extent-mapped and others are
indirect-block mapped. To address this, add a safety clamp in
ext4_mb_scan_groups().
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 9d89b9d55e25cb340c5b4b769876edc551b7a9ff Version: 1b0edd6022a3f44ce87fea9959a9310f4628fbea Version: 9eea2f57d11b30049ff996ac3eff6e0dc8089e5f Version: 34c803edc0b3365a42efcf9815acab63b4cf54e0 Version: 321ed8d559c951e71ad2d2d69a4cf0445644e865 Version: 4865c768b563deff1b6a6384e74a62f143427b42 Version: 16fce6b6c0b247258c6c217fce5a48abf50f6964 Version: 5.15.203 ≤ |
||
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-43067",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "yes"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-10-16T15:14:16.994971Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-822",
"description": "CWE-822 Untrusted Pointer Dereference",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-10-19T19:06:12.380Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/ext4/mballoc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "f89bba144938921a2249237ad04a0183ff3f8930",
"status": "affected",
"version": "9d89b9d55e25cb340c5b4b769876edc551b7a9ff",
"versionType": "git"
},
{
"lessThan": "83170a05908b6cf2fb3235d3065bf613ff866f3c",
"status": "affected",
"version": "1b0edd6022a3f44ce87fea9959a9310f4628fbea",
"versionType": "git"
},
{
"lessThan": "4bec4a498ce86314d470ae6144120461f2138c29",
"status": "affected",
"version": "9eea2f57d11b30049ff996ac3eff6e0dc8089e5f",
"versionType": "git"
},
{
"lessThan": "12624c5b724a81e14e532972b40d863b0de3b7d1",
"status": "affected",
"version": "34c803edc0b3365a42efcf9815acab63b4cf54e0",
"versionType": "git"
},
{
"lessThan": "2a368ccddfc492a0aa951e2caef2985f20e96503",
"status": "affected",
"version": "321ed8d559c951e71ad2d2d69a4cf0445644e865",
"versionType": "git"
},
{
"lessThan": "bb81702370fad22c06ca12b6e1648754dbc37e0f",
"status": "affected",
"version": "4865c768b563deff1b6a6384e74a62f143427b42",
"versionType": "git"
},
{
"status": "affected",
"version": "16fce6b6c0b247258c6c217fce5a48abf50f6964",
"versionType": "git"
},
{
"lessThan": "5.16",
"status": "affected",
"version": "5.15.203",
"versionType": "semver"
}
]
},
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/ext4/mballoc.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "6.1.168",
"status": "affected",
"version": "6.1.167",
"versionType": "semver"
},
{
"lessThan": "6.6.134",
"status": "affected",
"version": "6.6.130",
"versionType": "semver"
},
{
"lessThan": "6.12.80",
"status": "affected",
"version": "6.12.77",
"versionType": "semver"
},
{
"lessThan": "6.18.21",
"status": "affected",
"version": "6.18.14",
"versionType": "semver"
},
{
"lessThan": "6.19.11",
"status": "affected",
"version": "6.19.4",
"versionType": "semver"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.168",
"versionStartIncluding": "6.1.167",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.134",
"versionStartIncluding": "6.6.130",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.80",
"versionStartIncluding": "6.12.77",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.21",
"versionStartIncluding": "6.18.14",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.19.11",
"versionStartIncluding": "6.19.4",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "5.15.203",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: handle wraparound when searching for blocks for indirect mapped blocks\n\nCommit 4865c768b563 (\"ext4: always allocate blocks only from groups\ninode can use\") restricts what blocks will be allocated for indirect\nblock based files to block numbers that fit within 32-bit block\nnumbers.\n\nHowever, when using a review bot running on the latest Gemini LLM to\ncheck this commit when backporting into an LTS based kernel, it raised\nthis concern:\n\n If ac-\u003eac_g_ex.fe_group is \u003e= ngroups (for instance, if the goal\n group was populated via stream allocation from s_mb_last_groups),\n then start will be \u003e= ngroups.\n\n Does this allow allocating blocks beyond the 32-bit limit for\n indirect block mapped files? The commit message mentions that\n ext4_mb_scan_groups_linear() takes care to not select unsupported\n groups. However, its loop uses group = *start, and the very first\n iteration will call ext4_mb_scan_group() with this unsupported\n group because next_linear_group() is only called at the end of the\n iteration.\n\nAfter reviewing the code paths involved and considering the LLM\nreview, I determined that this can happen when there is a file system\nwhere some files/directories are extent-mapped and others are\nindirect-block mapped. To address this, add a safety clamp in\next4_mb_scan_groups()."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - In a reasonable high-impact deployment, a writable ext4 filesystem can be exported by in-kernel NFS or ksmbd, whose WRITE handlers enter the same VFS/ext4 allocation path. Local writes also reach it, but network is the highest defensible vector for an exported writable share.\nAC:L - Once the affected large mixed-format ext4 filesystem state exists, triggering is a normal file allocation/write path with no race or probabilistic memory condition. The attacker can drive stream allocation and indirect-file allocation through repeated writes.\nPR:N - A writable anonymous or guest NFS/SMB export can reach the vulnerable write path without local credentials or kernel capabilities. Even locally, only ordinary write permission to an affected file is needed, not administrative privilege.\nUI:N - No victim action is required after the vulnerable filesystem/share is available. The attacker triggers allocation directly by writing data.\nS:U - The impact remains within the kernel/filesystem security authority. This is not a VM escape, IOMMU bypass, or cross-authority sandbox escape.\nC:H - The bug can allocate a physical block above the 32-bit indirect-block limit and then store it through a 32-bit indirect pointer, wrapping the file mapping to another on-disk block. That can expose arbitrary file data from the same filesystem through the attacker\u0027s file.\nI:H - The wrapped indirect pointer can make attacker writes target blocks that were not actually allocated to the file. This can overwrite other file data or corrupt the filesystem.\nA:H - Filesystem corruption can make data unavailable and can force ext4 errors or read-only/remediation states. Repeated writes can reliably recreate the corruption on an affected deployment."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T12:25:42.475Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/f89bba144938921a2249237ad04a0183ff3f8930"
},
{
"url": "https://git.kernel.org/stable/c/83170a05908b6cf2fb3235d3065bf613ff866f3c"
},
{
"url": "https://git.kernel.org/stable/c/4bec4a498ce86314d470ae6144120461f2138c29"
},
{
"url": "https://git.kernel.org/stable/c/12624c5b724a81e14e532972b40d863b0de3b7d1"
},
{
"url": "https://git.kernel.org/stable/c/2a368ccddfc492a0aa951e2caef2985f20e96503"
},
{
"url": "https://git.kernel.org/stable/c/bb81702370fad22c06ca12b6e1648754dbc37e0f"
}
],
"title": "ext4: handle wraparound when searching for blocks for indirect mapped blocks",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-43067",
"datePublished": "2026-05-05T15:23:26.717Z",
"dateReserved": "2026-05-01T14:12:55.981Z",
"dateUpdated": "2026-10-19T19:06:12.380Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"vulnrichment": {
"containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-43067\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-10-16T15:14:16.994971Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-822\", \"description\": \"CWE-822 Untrusted Pointer Dereference\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-10-16T15:14:17.573Z\"}}], \"cna\": {\"title\": \"ext4: handle wraparound when searching for blocks for indirect mapped blocks\", \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 9.8, \"baseSeverity\": \"CRITICAL\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"AV:N - In a reasonable high-impact deployment, a writable ext4 filesystem can be exported by in-kernel NFS or ksmbd, whose WRITE handlers enter the same VFS/ext4 allocation path. Local writes also reach it, but network is the highest defensible vector for an exported writable share.\\nAC:L - Once the affected large mixed-format ext4 filesystem state exists, triggering is a normal file allocation/write path with no race or probabilistic memory condition. The attacker can drive stream allocation and indirect-file allocation through repeated writes.\\nPR:N - A writable anonymous or guest NFS/SMB export can reach the vulnerable write path without local credentials or kernel capabilities. Even locally, only ordinary write permission to an affected file is needed, not administrative privilege.\\nUI:N - No victim action is required after the vulnerable filesystem/share is available. The attacker triggers allocation directly by writing data.\\nS:U - The impact remains within the kernel/filesystem security authority. This is not a VM escape, IOMMU bypass, or cross-authority sandbox escape.\\nC:H - The bug can allocate a physical block above the 32-bit indirect-block limit and then store it through a 32-bit indirect pointer, wrapping the file mapping to another on-disk block. That can expose arbitrary file data from the same filesystem through the attacker\u0027s file.\\nI:H - The wrapped indirect pointer can make attacker writes target blocks that were not actually allocated to the file. This can overwrite other file data or corrupt the filesystem.\\nA:H - Filesystem corruption can make data unavailable and can force ext4 errors or read-only/remediation states. Repeated writes can reliably recreate the corruption on an affected deployment.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"9d89b9d55e25cb340c5b4b769876edc551b7a9ff\", \"lessThan\": \"f89bba144938921a2249237ad04a0183ff3f8930\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"1b0edd6022a3f44ce87fea9959a9310f4628fbea\", \"lessThan\": \"83170a05908b6cf2fb3235d3065bf613ff866f3c\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"9eea2f57d11b30049ff996ac3eff6e0dc8089e5f\", \"lessThan\": \"4bec4a498ce86314d470ae6144120461f2138c29\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"34c803edc0b3365a42efcf9815acab63b4cf54e0\", \"lessThan\": \"12624c5b724a81e14e532972b40d863b0de3b7d1\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"321ed8d559c951e71ad2d2d69a4cf0445644e865\", \"lessThan\": \"2a368ccddfc492a0aa951e2caef2985f20e96503\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"4865c768b563deff1b6a6384e74a62f143427b42\", \"lessThan\": \"bb81702370fad22c06ca12b6e1648754dbc37e0f\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"16fce6b6c0b247258c6c217fce5a48abf50f6964\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5.15.203\", \"lessThan\": \"5.16\", \"versionType\": \"semver\"}], \"programFiles\": [\"fs/ext4/mballoc.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\"}, {\"status\": \"affected\", \"version\": \"6.6.130\", \"lessThan\": \"6.6.134\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"6.12.77\", \"lessThan\": \"6.12.80\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"6.18.14\", \"lessThan\": \"6.18.21\", \"versionType\": \"semver\"}, {\"status\": \"affected\", \"version\": \"6.19.4\", \"lessThan\": \"6.19.11\", \"versionType\": \"semver\"}], \"programFiles\": [\"fs/ext4/mballoc.c\"], \"defaultStatus\": \"unaffected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/f89bba144938921a2249237ad04a0183ff3f8930\"}, {\"url\": \"https://git.kernel.org/stable/c/83170a05908b6cf2fb3235d3065bf613ff866f3c\"}, {\"url\": \"https://git.kernel.org/stable/c/4bec4a498ce86314d470ae6144120461f2138c29\"}, {\"url\": \"https://git.kernel.org/stable/c/12624c5b724a81e14e532972b40d863b0de3b7d1\"}, {\"url\": \"https://git.kernel.org/stable/c/2a368ccddfc492a0aa951e2caef2985f20e96503\"}, {\"url\": \"https://git.kernel.org/stable/c/bb81702370fad22c06ca12b6e1648754dbc37e0f\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\next4: handle wraparound when searching for blocks for indirect mapped blocks\\n\\nCommit 4865c768b563 (\\\"ext4: always allocate blocks only from groups\\ninode can use\\\") restricts what blocks will be allocated for indirect\\nblock based files to block numbers that fit within 32-bit block\\nnumbers.\\n\\nHowever, when using a review bot running on the latest Gemini LLM to\\ncheck this commit when backporting into an LTS based kernel, it raised\\nthis concern:\\n\\n If ac-\u003eac_g_ex.fe_group is \u003e= ngroups (for instance, if the goal\\n group was populated via stream allocation from s_mb_last_groups),\\n then start will be \u003e= ngroups.\\n\\n Does this allow allocating blocks beyond the 32-bit limit for\\n indirect block mapped files? The commit message mentions that\\n ext4_mb_scan_groups_linear() takes care to not select unsupported\\n groups. However, its loop uses group = *start, and the very first\\n iteration will call ext4_mb_scan_group() with this unsupported\\n group because next_linear_group() is only called at the end of the\\n iteration.\\n\\nAfter reviewing the code paths involved and considering the LLM\\nreview, I determined that this can happen when there is a file system\\nwhere some files/directories are extent-mapped and others are\\nindirect-block mapped. To address this, add a safety clamp in\\next4_mb_scan_groups().\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.168\", \"versionStartIncluding\": \"6.1.167\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.134\", \"versionStartIncluding\": \"6.6.130\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.80\", \"versionStartIncluding\": \"6.12.77\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.18.21\", \"versionStartIncluding\": \"6.18.14\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.19.11\", \"versionStartIncluding\": \"6.19.4\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionStartIncluding\": \"5.15.203\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T12:25:42.475Z\"}}}",
"cveMetadata": "{\"cveId\": \"CVE-2026-43067\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-19T19:06:12.380Z\", \"dateReserved\": \"2026-05-01T14:12:55.981Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-05-05T15:23:26.717Z\", \"assignerShortName\": \"Linux\"}",
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
Loading…
Loading…