CVE-2025-21945 (GCVE-0-2025-21945)
Vulnerability from cvelistv5 – Published: 2025-04-01 15:41 – Updated: 2026-08-05 11:55
VLAI
EPSS
VEX
Title
ksmbd: fix use-after-free in smb2_lock
Summary
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix use-after-free in smb2_lock
If smb_lock->zero_len has value, ->llist of smb_lock is not delete and
flock is old one. It will cause use-after-free on error handling
routine.
Severity
8.8 (High)
7.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-04-16 13:14 UTC
CWE
- CWE-416 - Use After Free
Assigner
References
6 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
0626e6641f6b467447c81dd7678a69c66f7746cf , < 410ce35a2ed6d0e114132bba29af49b69880c8c7
(git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 8573571060ca466cbef2c6f03306b2cc7b883506 (git) Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < a0609097fd10d618aed4864038393dd75131289e (git) Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 636e021646cf9b52ddfea7c809b018e91f2188cb (git) Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 84d2d1641b71dec326e8736a749b7ee76a9599fc (git) |
guessed | |
| Linux | Linux |
Affected:
5.15
Unaffected: 0 , < 5.15 (semver) Unaffected: 6.1.131 , ≤ 6.1.* (semver) Unaffected: 6.6.83 , ≤ 6.6.* (semver) Unaffected: 6.12.19 , ≤ 6.12.* (semver) Unaffected: 6.13.7 , ≤ 6.13.* (semver) Unaffected: 6.14 , ≤ * (original_commit_for_fix) |
guessed |
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"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
}
]
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-07-30T09:38:29+00:00",
"cve": "CVE-2025-21945",
"id": "CVE-2025-21945",
"initial_release_date": "2025-04-01T00:00:00+00:00",
"product_status:known_not_affected": "274",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: ksmbd: fix use-after-free in smb2_lock",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-21945.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"providerMetadata": {
"dateUpdated": "2025-11-03T19:39:45.983Z",
"orgId": "af854a3a-2127-422b-91ae-364da2661108",
"shortName": "CVE"
},
"references": [
{
"url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"
}
],
"title": "CVE Program Container"
},
{
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
}
},
{
"other": {
"content": {
"id": "CVE-2025-21945",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2025-04-16T13:14:55.516245Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-416",
"description": "CWE-416 Use After Free",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2025-04-16T13:14:56.950Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"fs/smb/server/smb2pdu.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "410ce35a2ed6d0e114132bba29af49b69880c8c7",
"status": "affected",
"version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
"versionType": "git"
},
{
"lessThan": "8573571060ca466cbef2c6f03306b2cc7b883506",
"status": "affected",
"version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
"versionType": "git"
},
{
"lessThan": "a0609097fd10d618aed4864038393dd75131289e",
"status": "affected",
"version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
"versionType": "git"
},
{
"lessThan": "636e021646cf9b52ddfea7c809b018e91f2188cb",
"status": "affected",
"version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
"versionType": "git"
},
{
"lessThan": "84d2d1641b71dec326e8736a749b7ee76a9599fc",
"status": "affected",
"version": "0626e6641f6b467447c81dd7678a69c66f7746cf",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"fs/smb/server/smb2pdu.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.15"
},
{
"lessThan": "5.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.131",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.83",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.19",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.13.*",
"status": "unaffected",
"version": "6.13.7",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.14",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.131",
"versionStartIncluding": "5.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.83",
"versionStartIncluding": "5.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.19",
"versionStartIncluding": "5.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.13.7",
"versionStartIncluding": "5.15",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.14",
"versionStartIncluding": "5.15",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: fix use-after-free in smb2_lock\n\nIf smb_lock-\u003ezero_len has value, -\u003ellist of smb_lock is not delete and\nflock is old one. It will cause use-after-free on error handling\nroutine."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:N - ksmbd is the in-kernel SMB server listening on TCP/445, and the entire bug is triggered by a single crafted SMB2 LOCK PDU whose lock elements carry Length==0 and attacker-chosen flags. No local access to the target is needed.\nAC:L - The zero_len path is taken deterministically whenever the client sets a lock element\u0027s Length to 0, and the stale `flock`/`flags` reuse and skipped `list_del` follow unconditionally; there is no race and the attacker can repeat the request indefinitely to groom the heap.\nPR:L - SMB2_LOCK is gated by smb2_check_user_session() and requires an open file handle from ksmbd_lookup_fd_slow(), so the attacker needs valid credentials for an exported share \u2014 an ordinary low-privileged SMB account, not administrative rights.\nUI:N - The attacker drives the whole sequence (session setup, tree connect, create, lock) from its own connection; no action by any local user or administrator is required.\nS:U - The corruption is confined to kernel heap objects managed by the SMB server and the VFS lock layer, within the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed ksmbd_lock stays linked in lock_list and in the global per-connection lock_list, and the stale file_lock is re-read by vfs_lock_file() and by other connections\u0027 conflict scans, so reclaimed heap contents are dereferenced and can be leveraged to disclose kernel memory.\nI:H - The dangling entries produce a double-free plus list_del writes through attacker-groomable freed slab objects, giving the write primitives needed to corrupt adjacent kernel structures and hijack control flow.\nA:H - Use of freed ksmbd_lock/file_lock memory and the resulting double-free and corrupted list traversals reliably oops or panic the kernel, taking down the whole file server."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-05T11:55:30.419Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/410ce35a2ed6d0e114132bba29af49b69880c8c7"
},
{
"url": "https://git.kernel.org/stable/c/8573571060ca466cbef2c6f03306b2cc7b883506"
},
{
"url": "https://git.kernel.org/stable/c/a0609097fd10d618aed4864038393dd75131289e"
},
{
"url": "https://git.kernel.org/stable/c/636e021646cf9b52ddfea7c809b018e91f2188cb"
},
{
"url": "https://git.kernel.org/stable/c/84d2d1641b71dec326e8736a749b7ee76a9599fc"
}
],
"title": "ksmbd: fix use-after-free in smb2_lock",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-21945",
"datePublished": "2025-04-01T15:41:08.471Z",
"dateReserved": "2024-12-29T08:45:45.790Z",
"dateUpdated": "2026-08-05T11:55:30.419Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
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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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