CVE-2025-40139 (GCVE-0-2025-40139)
Vulnerability from cvelistv5 – Published: 2025-11-12 10:23 – Updated: 2026-09-02 12:49
VLAI
EPSS
VEX
Title
smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().
Summary
In the Linux kernel, the following vulnerability has been resolved:
smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().
smc_clc_prfx_set() is called during connect() and not under RCU
nor RTNL.
Using sk_dst_get(sk)->dev could trigger UAF.
Let's use __sk_dst_get() and dev_dst_rcu() under rcu_read_lock()
after kernel_getsockname().
Note that the returned value of smc_clc_prfx_set() is not used
in the caller.
While at it, we change the 1st arg of smc_clc_prfx_set[46]_rcu()
not to touch dst there.
Severity
7.8 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
a046d57da19f812216f393e7c535f5858f793ac3 , < 5a2fccc4b32c13ddde3676f9e15e1a9baa7d6fde
(git)
Affected: a046d57da19f812216f393e7c535f5858f793ac3 , < 80d1fd39f4e37d836655e9f7ffccaf78925049bf (git) Affected: a046d57da19f812216f393e7c535f5858f793ac3 , < 956c57daba55cf9ed25d9f2512883b8a1a927599 (git) Affected: a046d57da19f812216f393e7c535f5858f793ac3 , < 0736993bfe5c7a9c744ae3fac62d769dfdae54e1 (git) Affected: a046d57da19f812216f393e7c535f5858f793ac3 , < 935d783e5de9b64587f3adb25641dd8385e64ddb (git) |
guessed | |
| Linux | Linux |
Affected:
4.11
Unaffected: 0 , < 4.11 (semver) Unaffected: 6.1.187 , ≤ 6.1.* (semver) Unaffected: 6.6.156 , ≤ 6.6.* (semver) Unaffected: 6.12.108 , ≤ 6.12.* (semver) Unaffected: 6.17.3 , ≤ 6.17.* (semver) Unaffected: 6.18 , ≤ * (original_commit_for_fix) |
guessed |
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
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{
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"versionType": "semver"
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"status": "unaffected",
"version": "6.17.3",
"versionType": "semver"
},
{
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"status": "unaffected",
"version": "6.18",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
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{
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"versionStartIncluding": "4.11",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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{
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"versionStartIncluding": "4.11",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().\n\nsmc_clc_prfx_set() is called during connect() and not under RCU\nnor RTNL.\n\nUsing sk_dst_get(sk)-\u003edev could trigger UAF.\n\nLet\u0027s use __sk_dst_get() and dev_dst_rcu() under rcu_read_lock()\nafter kernel_getsockname().\n\nNote that the returned value of smc_clc_prfx_set() is not used\nin the caller.\n\nWhile at it, we change the 1st arg of smc_clc_prfx_set[46]_rcu()\nnot to touch dst there."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:L - `smc_clc_prfx_set()` is only reached from the client side of the CLC handshake, via `connect()` on a locally created AF_SMC socket (`smc_connect` \u2192 `__smc_connect` \u2192 `smc_clc_send_proposal`). The attacker must have local code execution to initiate the connection, so the vector is Local even though the leaked bytes are subsequently sent to a remote peer.\nAC:L - The attacker drives both sides of the race \u2014 one thread loops `connect()` on AF_SMC sockets (the stale `dst-\u003edev` dereference), while another repeatedly creates and deletes net_devices to force `dst_dev_put()`/`free_netdev()`, which unprivileged users can do freely inside a user namespace with CAP_NET_ADMIN. No condition depends on state outside the attacker\u0027s influence, and the window is widened at will by using non-blocking connect so the work runs in `smc_connect_work`.\nPR:L - `smc_create()` performs no capability check and `MODULE_ALIAS_NETPROTO(PF_SMC)` lets any unprivileged user autoload the module; the netdev teardown side needs CAP_NET_ADMIN, which is obtainable by an ordinary user via `unshare -Urn` and therefore counts as Low, not High.\nUI:N - The attacker\u0027s own process performs every step \u2014 creating the SMC socket, connecting to a listener it controls, and tearing down the device \u2014 with no action required from any other user or administrator.\nS:U - The use-after-free touches the freed `net_device` slab and the `in_device`/`inet6_dev` structures it points to, all within the kernel\u0027s own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed `net_device` is dereferenced and its `ifa_list`/`addr_list` walked, and a reclaimed slab can be groomed with attacker-controlled data, yielding an arbitrary kernel-memory read; worse, `smc_clc_prfx_set6_rcu()` copies up to 8 prefixes out of that freed memory into the CLC Proposal that `smc_clc_send_proposal()` transmits, exfiltrating freed kernel bytes onto the wire.\nI:H - A use-after-free on a `net_device` is a heap-corruption primitive \u2014 the reclaimed object\u0027s contents are attacker-influenceable through heap spraying and the code follows pointers out of it (`dev-\u003eip_ptr`, `dev-\u003eip6_ptr`, list heads), which can be groomed into an arbitrary write and control-flow hijack.\nA:H - Dereferencing the freed device and walking a bogus `in_dev`/`inet6_dev` address list reliably produces a kernel oops or panic, or an unbounded list walk that hangs the CPU, and the attacker can repeat the attempt indefinitely."
}
]
}
],
"providerMetadata": {
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"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
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"url": "https://git.kernel.org/stable/c/5a2fccc4b32c13ddde3676f9e15e1a9baa7d6fde"
},
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"url": "https://git.kernel.org/stable/c/80d1fd39f4e37d836655e9f7ffccaf78925049bf"
},
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"url": "https://git.kernel.org/stable/c/956c57daba55cf9ed25d9f2512883b8a1a927599"
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{
"url": "https://git.kernel.org/stable/c/0736993bfe5c7a9c744ae3fac62d769dfdae54e1"
},
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"url": "https://git.kernel.org/stable/c/935d783e5de9b64587f3adb25641dd8385e64ddb"
}
],
"title": "smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().",
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"cveId": "CVE-2025-40139",
"datePublished": "2025-11-12T10:23:24.216Z",
"dateReserved": "2025-04-16T07:20:57.171Z",
"dateUpdated": "2026-09-02T12:49:26.951Z",
"state": "PUBLISHED"
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"vulnerability-lookup:meta": {
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"cve": "CVE-2025-40139",
"date": "2026-09-21",
"epss": "0.00153",
"percentile": "0.04794"
},
"microsoft_vex": {
"current_release_date": "2026-06-28T01:50:41.000Z",
"cve": "CVE-2025-40139",
"id": "msrc_CVE-2025-40139",
"initial_release_date": "2025-11-02T00:00:00.000Z",
"product_status:known_affected": "13",
"source": "Microsoft CSAF VEX",
"status": "final",
"title": "smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().",
"url": "https://msrc.microsoft.com/csaf/vex/2025/msrc_cve-2025-40139.json",
"version": "14"
},
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"descriptions": [
{
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set().\n\nsmc_clc_prfx_set() is called during connect() and not under RCU\nnor RTNL.\n\nUsing sk_dst_get(sk)-\u003edev could trigger UAF.\n\nLet\u0027s use __sk_dst_get() and dev_dst_rcu() under rcu_read_lock()\nafter kernel_getsockname().\n\nNote that the returned value of smc_clc_prfx_set() is not used\nin the caller.\n\nWhile at it, we change the 1st arg of smc_clc_prfx_set[46]_rcu()\nnot to touch dst there."
}
],
"id": "CVE-2025-40139",
"lastModified": "2026-09-02T13:16:50.347",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"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"
},
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"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
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},
"published": "2025-11-12T11:15:43.677",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/0736993bfe5c7a9c744ae3fac62d769dfdae54e1"
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},
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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},
{
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],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Deferred"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-07-30T08:48:08+00:00",
"cve": "CVE-2025-40139",
"id": "CVE-2025-40139",
"initial_release_date": "2025-11-12T00:00:00+00:00",
"product_status:known_affected": "232",
"product_status:known_not_affected": "42",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: smc: Use __sk_dst_get() and dst_dev_rcu() in in smc_clc_prfx_set()",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40139.json",
"version": "3"
}
}
}
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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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