FKIE_CVE-2026-98171
Vulnerability from fkie_nvd - Published: 2026-10-06 09:17 - Updated: 2026-10-07 07:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs
Fix several related bounds checking and pointer lifecycle issues in
receive_encrypted_standard()'s handling of compound encrypted frames:
- Clear next_buffer after assigning it to server->bigbuf. A stale
next_buffer pointer can lead to a use-after-free on subsequent
error paths.
- Update pdu_length to the decrypted plaintext size (buf_size). Using
the pre-decryption length allows NextCommand to point into stale
ciphertext residue.
- Reject next_cmd values smaller than MID_HEADER_SIZE(server).
- Fix an integer overflow in the upper bound check by verifying
pdu_length - next_cmd < MID_HEADER_SIZE(server), ensuring the
trailing slice is large enough for a header.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/smb/client/smb2ops.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "72eaef1f37a3b6bec11c342736834dc3707be3e4",
"status": "affected",
"version": "b24df3e30cbf48255db866720fb71f14bf9d2f39",
"versionType": "git"
},
{
"lessThan": "491e33144dee872cffda207f6fcb09260728f803",
"status": "affected",
"version": "b24df3e30cbf48255db866720fb71f14bf9d2f39",
"versionType": "git"
},
{
"lessThan": "8749946579708ea0d339034bb7f423a67dbe89cf",
"status": "affected",
"version": "b24df3e30cbf48255db866720fb71f14bf9d2f39",
"versionType": "git"
},
{
"lessThan": "96c436e4b010711452b2872558938f4ef276492a",
"status": "affected",
"version": "b24df3e30cbf48255db866720fb71f14bf9d2f39",
"versionType": "git"
},
{
"lessThan": "858d5ac22cb889266993e7670f9f0c4f4aeedd78",
"status": "affected",
"version": "b24df3e30cbf48255db866720fb71f14bf9d2f39",
"versionType": "git"
},
{
"lessThan": "05762c5bc1cfdcac36747994fde2c04387a457f1",
"status": "affected",
"version": "b24df3e30cbf48255db866720fb71f14bf9d2f39",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/smb/client/smb2ops.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.19"
},
{
"lessThan": "4.19",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.189",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.112",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.54",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.8",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3-rc4",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs\n\nFix several related bounds checking and pointer lifecycle issues in\nreceive_encrypted_standard()\u0027s handling of compound encrypted frames:\n\n- Clear next_buffer after assigning it to server-\u003ebigbuf. A stale\n next_buffer pointer can lead to a use-after-free on subsequent\n error paths.\n- Update pdu_length to the decrypted plaintext size (buf_size). Using\n the pre-decryption length allows NextCommand to point into stale\n ciphertext residue.\n- Reject next_cmd values smaller than MID_HEADER_SIZE(server).\n- Fix an integer overflow in the upper bound check by verifying\n pdu_length - next_cmd \u003c MID_HEADER_SIZE(server), ensuring the\n trailing slice is large enough for a header."
}
],
"id": "CVE-2026-98171",
"lastModified": "2026-10-07T07:17:03.600",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "REQUIRED",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-10-06T09:17:58.773",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/05762c5bc1cfdcac36747994fde2c04387a457f1"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/491e33144dee872cffda207f6fcb09260728f803"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/72eaef1f37a3b6bec11c342736834dc3707be3e4"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/858d5ac22cb889266993e7670f9f0c4f4aeedd78"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/8749946579708ea0d339034bb7f423a67dbe89cf"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/96c436e4b010711452b2872558938f4ef276492a"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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