FKIE_CVE-2026-74493
Vulnerability from fkie_nvd - Published: 2026-08-15 13:17 - Updated: 2026-08-17 06:19
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/smc: fix socket use-after-free during link group termination
__smc_lgr_terminate() drops conns_lock after finding a connection in
lgr->conns_all, but before taking a reference on its socket. The connection
is embedded in the socket, and its registration reference protects it only
while the connection remains in the tree.
A concurrent close can unregister the connection and drop that reference,
freeing the socket before the termination worker reaches sock_hold().
The race is reachable when close overlaps link group termination.
Local stress testing reproduced the use-after-free and KASAN reported:
BUG: KASAN: slab-use-after-free in __smc_lgr_terminate.part.0 [smc]
Write of size 4 by task kworker/3:3
Workqueue: events smc_lgr_terminate_work [smc]
__smc_lgr_terminate.part.0 [smc]
The socket was allocated by smc_create(), freed through
slab_free_after_rcu_debug(), and was followed by:
refcount_t: addition on 0; use-after-free.
__smc_lgr_terminate.part.0 [smc]
Take the socket reference while conns_lock still protects the tree entry.
The unregister path then cannot drop the last reference until termination
has finished using the socket.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/smc/smc_core.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "5a42f162b857019a4c10ff687dc3bcdf51831865",
"status": "affected",
"version": "69318b5215f2dc32c345a3d65b98b4b1bf29c007",
"versionType": "git"
},
{
"lessThan": "281c103a8eaed59001ce952f231df1b07674215a",
"status": "affected",
"version": "69318b5215f2dc32c345a3d65b98b4b1bf29c007",
"versionType": "git"
},
{
"lessThan": "f807a63d0d95680c34f677700da9148a07d7c78f",
"status": "affected",
"version": "69318b5215f2dc32c345a3d65b98b4b1bf29c007",
"versionType": "git"
},
{
"lessThan": "f0541a775d04c88e90ba448e35ce0d743512822a",
"status": "affected",
"version": "69318b5215f2dc32c345a3d65b98b4b1bf29c007",
"versionType": "git"
},
{
"lessThan": "f621d6ebeebb6374342571e4ddf45fdbc420f6cd",
"status": "affected",
"version": "69318b5215f2dc32c345a3d65b98b4b1bf29c007",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/smc/smc_core.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "5.5"
},
{
"lessThan": "5.5",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.151",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.103",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.44",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.8",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"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\nnet/smc: fix socket use-after-free during link group termination\n\n__smc_lgr_terminate() drops conns_lock after finding a connection in\nlgr-\u003econns_all, but before taking a reference on its socket. The connection\nis embedded in the socket, and its registration reference protects it only\nwhile the connection remains in the tree.\n\nA concurrent close can unregister the connection and drop that reference,\nfreeing the socket before the termination worker reaches sock_hold().\n\nThe race is reachable when close overlaps link group termination.\nLocal stress testing reproduced the use-after-free and KASAN reported:\n\n BUG: KASAN: slab-use-after-free in __smc_lgr_terminate.part.0 [smc]\n Write of size 4 by task kworker/3:3\n Workqueue: events smc_lgr_terminate_work [smc]\n __smc_lgr_terminate.part.0 [smc]\n\nThe socket was allocated by smc_create(), freed through\nslab_free_after_rcu_debug(), and was followed by:\n\n refcount_t: addition on 0; use-after-free.\n __smc_lgr_terminate.part.0 [smc]\n\nTake the socket reference while conns_lock still protects the tree entry.\nThe unregister path then cannot drop the last reference until termination\nhas finished using the socket."
}
],
"id": "CVE-2026-74493",
"lastModified": "2026-08-17T06:19:45.623",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-08-15T13:17:54.240",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/281c103a8eaed59001ce952f231df1b07674215a"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/5a42f162b857019a4c10ff687dc3bcdf51831865"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/f0541a775d04c88e90ba448e35ce0d743512822a"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/f621d6ebeebb6374342571e4ddf45fdbc420f6cd"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/f807a63d0d95680c34f677700da9148a07d7c78f"
}
],
"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.
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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