CVE-2025-40328 (GCVE-0-2025-40328)
Vulnerability from cvelistv5 – Published: 2025-12-09 04:09 – Updated: 2026-08-05 12:09
VLAI
EPSS
VEX
Title
smb: client: fix potential UAF in smb2_close_cached_fid()
Summary
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix potential UAF in smb2_close_cached_fid()
find_or_create_cached_dir() could grab a new reference after kref_put()
had seen the refcount drop to zero but before cfid_list_lock is acquired
in smb2_close_cached_fid(), leading to use-after-free.
Switch to kref_put_lock() so cfid_release() is called with
cfid_list_lock held, closing that gap.
Severity
8.8 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
ebe98f1447bbccf8228335c62d86af02a0ed23f7 , < cb52d9c86d70298de0ab7c7953653898cbc0efd6
(git)
Affected: ebe98f1447bbccf8228335c62d86af02a0ed23f7 , < 065bd62412271a2d734810dd50336cae88c54427 (git) Affected: ebe98f1447bbccf8228335c62d86af02a0ed23f7 , < bdb596ceb4b7c3f28786a33840263728217fbcf5 (git) Affected: ebe98f1447bbccf8228335c62d86af02a0ed23f7 , < 734e99623c5b65bf2c03e35978a0b980ebc3c2f8 (git) |
guessed | |
| Linux | Linux |
Affected:
6.1
Unaffected: 0 , < 6.1 (semver) Unaffected: 6.6.117 , ≤ 6.6.* (semver) Unaffected: 6.12.58 , ≤ 6.12.* (semver) Unaffected: 6.17.8 , ≤ 6.17.* (semver) Unaffected: 6.18 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/smb/client/cached_dir.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "cb52d9c86d70298de0ab7c7953653898cbc0efd6",
"status": "affected",
"version": "ebe98f1447bbccf8228335c62d86af02a0ed23f7",
"versionType": "git"
},
{
"lessThan": "065bd62412271a2d734810dd50336cae88c54427",
"status": "affected",
"version": "ebe98f1447bbccf8228335c62d86af02a0ed23f7",
"versionType": "git"
},
{
"lessThan": "bdb596ceb4b7c3f28786a33840263728217fbcf5",
"status": "affected",
"version": "ebe98f1447bbccf8228335c62d86af02a0ed23f7",
"versionType": "git"
},
{
"lessThan": "734e99623c5b65bf2c03e35978a0b980ebc3c2f8",
"status": "affected",
"version": "ebe98f1447bbccf8228335c62d86af02a0ed23f7",
"versionType": "git"
}
]
},
{
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"product": "Linux",
"programFiles": [
"fs/smb/client/cached_dir.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.1"
},
{
"lessThan": "6.1",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.117",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.58",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.17.*",
"status": "unaffected",
"version": "6.17.8",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.117",
"versionStartIncluding": "6.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.58",
"versionStartIncluding": "6.1",
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.17.8",
"versionStartIncluding": "6.1",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18",
"versionStartIncluding": "6.1",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix potential UAF in smb2_close_cached_fid()\n\nfind_or_create_cached_dir() could grab a new reference after kref_put()\nhad seen the refcount drop to zero but before cfid_list_lock is acquired\nin smb2_close_cached_fid(), leading to use-after-free.\n\nSwitch to kref_put_lock() so cfid_release() is called with\ncfid_list_lock held, closing that gap."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - The freeing side of the race is driven directly by a remote peer \u2014 `smb2_is_valid_lease_break()` (fs/smb/client/smb2misc.c:692) processes unsolicited SMB2 lease-break packets from the server and calls `cached_dir_lease_break()`, which clears the lease ref and queues the final `kref_put()`; server-forced reconnects similarly drive `invalidate_all_cached_dirs()`. A malicious, compromised, or MITM\u0027d SMB server therefore triggers the vulnerable refcount transition over the network.\nAC:L - The attacker controls the timing and rate of lease breaks/reconnects and can replay them indefinitely against routine directory activity on the mount, so the narrow window between `refcount_dec_and_test()` and the lock acquisition can be hit reliably by repetition. Race conditions the attacker can retry at will are Low complexity.\nPR:N - A malicious or MITM SMB server needs no credentials or privileges on the victim host; lease-break notifications are unsolicited server-to-client messages processed by the demultiplex thread. In the local variant the trigger is plain rmdir/stat/readdir on an accessible mount, requiring at most an unprivileged account.\nUI:R - Exploitation requires the victim to have the attacker-controlled SMB share mounted and to be performing directory lookups on it so that `find_or_create_cached_dir()` runs concurrently with the release path. The server cannot force that local access itself.\nS:U - The use-after-free is on a kernel slab object (`struct cached_fid`) and the impact stays within the kernel\u0027s own security authority \u2014 no VM, IOMMU, or sandbox boundary is crossed.\nC:H - A freed `cached_fid` holding `dentry`, `tcon`, `cifs_fid` handles, a mutex and list/work heads can be reallocated and sprayed with attacker-chosen data; the racing thread then reads it and returns cached directory/file_all_info state, giving a path to disclosing kernel memory. Per guidance, use-after-free is scored High for confidentiality.\nI:H - The stale object is written through as well as read (`kref_get`, `last_access_time`, list manipulation, `dput(cfid-\u003edentry)` on a reused pointer, and `SMB2_close()` on stale fid values), so heap grooming turns this into a write primitive over reallocated slab contents and potential control-flow hijack via the embedded `work_struct` function pointers.\nA:H - Losing the race produces a `refcount_t: addition on 0` warning followed by dereference and double-free of the `cached_fid` \u2014 including `dput()` on a freed dentry and slab corruption \u2014 reliably causing an oops or kernel panic."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T12:09:39.443Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/cb52d9c86d70298de0ab7c7953653898cbc0efd6"
},
{
"url": "https://git.kernel.org/stable/c/065bd62412271a2d734810dd50336cae88c54427"
},
{
"url": "https://git.kernel.org/stable/c/bdb596ceb4b7c3f28786a33840263728217fbcf5"
},
{
"url": "https://git.kernel.org/stable/c/734e99623c5b65bf2c03e35978a0b980ebc3c2f8"
}
],
"title": "smb: client: fix potential UAF in smb2_close_cached_fid()",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-40328",
"datePublished": "2025-12-09T04:09:44.876Z",
"dateReserved": "2025-04-16T07:20:57.186Z",
"dateUpdated": "2026-08-05T12:09:39.443Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2025-40328",
"date": "2026-09-15",
"epss": "0.00461",
"percentile": "0.38794"
},
"nvd": "{\"cve\":{\"id\":\"CVE-2025-40328\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-12-09T16:17:42.903\",\"lastModified\":\"2026-07-30T06:24:29.547\",\"vulnStatus\":\"Deferred\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nsmb: client: fix potential UAF in smb2_close_cached_fid()\\n\\nfind_or_create_cached_dir() could grab a new reference after kref_put()\\nhad seen the refcount drop to zero but before cfid_list_lock is acquired\\nin smb2_close_cached_fid(), leading to use-after-free.\\n\\nSwitch to kref_put_lock() so cfid_release() is called with\\ncfid_list_lock held, closing that gap.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/smb/client/cached_dir.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"ebe98f1447bbccf8228335c62d86af02a0ed23f7\",\"lessThan\":\"cb52d9c86d70298de0ab7c7953653898cbc0efd6\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"ebe98f1447bbccf8228335c62d86af02a0ed23f7\",\"lessThan\":\"065bd62412271a2d734810dd50336cae88c54427\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"ebe98f1447bbccf8228335c62d86af02a0ed23f7\",\"lessThan\":\"bdb596ceb4b7c3f28786a33840263728217fbcf5\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"ebe98f1447bbccf8228335c62d86af02a0ed23f7\",\"lessThan\":\"734e99623c5b65bf2c03e35978a0b980ebc3c2f8\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/smb/client/cached_dir.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.1\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.1\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.117\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.58\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.17.8\",\"lessThanOrEqual\":\"6.17.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H\",\"baseScore\":8.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"REQUIRED\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/065bd62412271a2d734810dd50336cae88c54427\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/734e99623c5b65bf2c03e35978a0b980ebc3c2f8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/bdb596ceb4b7c3f28786a33840263728217fbcf5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/cb52d9c86d70298de0ab7c7953653898cbc0efd6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-08-21T20:04:51+00:00",
"cve": "CVE-2025-40328",
"id": "CVE-2025-40328",
"initial_release_date": "2025-12-09T00:00:00+00:00",
"product_status:known_affected": "184",
"product_status:known_not_affected": "90",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: smb: client: fix potential UAF in smb2_close_cached_fid()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40328.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "moderate",
"current_release_date": "2026-09-11T01:53:44Z",
"cve": "CVE-2025-40328",
"id": "CVE-2025-40328",
"initial_release_date": "2025-12-10T00:26:48Z",
"product_status:first_fixed": "2",
"product_status:known_affected": "569",
"product_status:known_not_affected": "260",
"product_status:recommended": "384",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2025-40328",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2025-40328.json",
"version": "43"
}
}
}
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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.
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.
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