CVE-2026-64391 (GCVE-0-2026-64391)
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:
ksmbd: use opener credentials for ADS I/O
Alternate data streams are stored as xattrs. Unlike regular file I/O,
their read and write paths therefore call VFS xattr helpers which recheck
inode permissions and LSM policy using the current task credentials.
Run ADS I/O with the credentials captured when the SMB handle was opened.
References
| URL | Tags | |
|---|---|---|
Impacted products
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"containers": {
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"version": "6.12.96",
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"status": "unaffected",
"version": "6.18.39",
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"status": "unaffected",
"version": "7.1.4",
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{
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"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
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"descriptions": [
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: use opener credentials for ADS I/O\n\nAlternate data streams are stored as xattrs. Unlike regular file I/O,\ntheir read and write paths therefore call VFS xattr helpers which recheck\ninode permissions and LSM policy using the current task credentials.\n\nRun ADS I/O with the credentials captured when the SMB handle was opened."
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"metrics": [
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"cvssV3_1": {
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"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"
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"value": "AV:N - An attacker reaches the vulnerable ADS read and write paths through SMB2 requests to an exposed ksmbd server over TCP/445.\nAC:L - Exploitation is deterministic using an ADS handle followed by ordinary SMB2 READ or WRITE requests; no race, memory-layout dependency, or condition outside the attacker\u0027s control is required.\nPR:N - Although a valid session, tree connection, and handle are required, a guest-enabled streams share permits a remote client to establish the necessary guest session without supplying valid credentials.\nUI:N - The attacker directly opens and accesses the alternate data stream through SMB requests without requiring any victim action.\nS:U - The credential bypass affects ADS data managed by the same host kernel and filesystem security authority; it does not cross a virtualization or comparable isolation boundary.\nC:H - Privileged worker credentials can bypass inode and LSM xattr checks and disclose the complete contents of an attacker-selected named stream, including potentially sensitive application data.\nI:H - The vulnerable write path can bypass xattr authorization and replace or truncate the complete named stream with attacker-controlled data.\nA:H - Repeated unauthorized truncation or corruption can persistently destroy an ADS and render applications or services that depend on that stream unusable until the data is restored."
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}
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"providerMetadata": {
"dateUpdated": "2026-08-17T04:54:43.832Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"references": [
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"url": "https://git.kernel.org/stable/c/a8f5d39971bbad9340d49cd41b0e2da9452a649d"
},
{
"url": "https://git.kernel.org/stable/c/2b4592cea214683de0f2ce6f8c22c097fb0ea1ab"
},
{
"url": "https://git.kernel.org/stable/c/52a56cf53ec834c44ac1b4d16d585f26613ee5ce"
},
{
"url": "https://git.kernel.org/stable/c/baa5e094886fffa7e6272edcb5e08be5ce28262c"
}
],
"title": "ksmbd: use opener credentials for ADS I/O",
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"cveId": "CVE-2026-64391",
"datePublished": "2026-07-25T08:50:38.013Z",
"dateReserved": "2026-07-19T15:36:31.785Z",
"dateUpdated": "2026-08-17T04:54:43.832Z",
"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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