CVE-2026-64380 (GCVE-0-2026-64380)
Vulnerability from cvelistv5
Published
2026-07-25 08:50
Modified
2026-08-17 04:54
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
smb: client: harden POSIX SID length parsing
posix_info_sid_size() reads sid[1] to obtain the subauthority count,
but its existing boundary check still accepts buffers with only one
remaining byte. Require two bytes before reading sid[1] so all client
paths that reuse the helper reject truncated POSIX SIDs safely.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: 349e13ad30b45998bb9937cfe0b32be6f951976d Version: 349e13ad30b45998bb9937cfe0b32be6f951976d Version: 349e13ad30b45998bb9937cfe0b32be6f951976d Version: 349e13ad30b45998bb9937cfe0b32be6f951976d Version: 349e13ad30b45998bb9937cfe0b32be6f951976d Version: 349e13ad30b45998bb9937cfe0b32be6f951976d Version: 349e13ad30b45998bb9937cfe0b32be6f951976d Version: 349e13ad30b45998bb9937cfe0b32be6f951976d |
||
{
"containers": {
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"programFiles": [
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],
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"vendor": "Linux",
"versions": [
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"version": "5.7"
},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "5.10.261",
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},
{
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"status": "unaffected",
"version": "5.15.212",
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},
{
"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",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
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"nodes": [
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}
],
"negate": false,
"operator": "OR"
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],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: harden POSIX SID length parsing\n\nposix_info_sid_size() reads sid[1] to obtain the subauthority count,\nbut its existing boundary check still accepts buffers with only one\nremaining byte. Require two bytes before reading sid[1] so all client\npaths that reuse the helper reject truncated POSIX SIDs safely."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.2,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - A malicious SMB server can deliver the truncated POSIX SID through SMB3.1.1 query-info or query-directory responses over TCP.\nAC:L - The server directly controls the response length and can deterministically leave exactly one SID byte remaining; no race or uncontrollable condition is required.\nPR:N - The malicious server needs no privileges on the vulnerable client, and guest-capable or attacker-controlled shares can supply the response after connection establishment.\nUI:N - On an already mounted POSIX-enabled share, routine automated stat, readdir, or metadata operations can trigger parsing without human interaction.\nS:U - The out-of-bounds access occurs within the client kernel and does not cross a virtualization, IOMMU, or other separate security authority boundary.\nC:L - The primitive reads exactly one byte beyond the response boundary, limiting any confidentiality effect to adjacent memory rather than providing an arbitrary-read primitive.\nI:N - The out-of-bounds byte only influences validation, which always rejects because a legal SID requires at least 12 bytes; no attacker-influenced copy or memory write follows.\nA:H - The server can place the truncated SID at the receive allocation boundary, where the out-of-bounds access can trigger a sanitizer fault or kernel oops and can be repeated to crash the client."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T04:54:31.740Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/171605aed68380c2fa75dff9b3a1ed427c50065b"
},
{
"url": "https://git.kernel.org/stable/c/4213c1208978483021d7d125c131de3985d38f61"
},
{
"url": "https://git.kernel.org/stable/c/96e889bc1e759c83f25093e8c2f3da31b4973f30"
},
{
"url": "https://git.kernel.org/stable/c/0de5b8e76847f5de26f364a82c6602c4881c30da"
},
{
"url": "https://git.kernel.org/stable/c/427eb7eb46425fec845a43e861f3d6e2899cae59"
},
{
"url": "https://git.kernel.org/stable/c/86c5d470f5d42e61123b2f4b4f0b91f4eee5b980"
},
{
"url": "https://git.kernel.org/stable/c/46a84715a015cb48e1b9c219dc88c03d8a541ea4"
},
{
"url": "https://git.kernel.org/stable/c/7ad2bcf2441430bb2e918fb3ef9a90d775a6e422"
}
],
"title": "smb: client: harden POSIX SID length parsing",
"x_generator": {
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}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-64380",
"datePublished": "2026-07-25T08:50:30.476Z",
"dateReserved": "2026-07-19T15:36:31.784Z",
"dateUpdated": "2026-08-17T04:54:31.740Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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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.
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