FKIE_CVE-2026-90325
Vulnerability from fkie_nvd - Published: 2026-09-17 17:17 - Updated: 2026-09-18 18:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
blk-cgroup: skip dying blkg in blkcg_activate_policy()
When switching IO schedulers on a block device, blkcg_activate_policy()
can race with concurrent blkcg deletion, leading to a use-after-free in
rcu_accelerate_cbs.
T1: T2:
blkg_destroy
kill(&blkg->refcnt) // blkg->refcnt=1->0
blkg_release // call_rcu(__blkg_release)
...
blkg_free_workfn
->pd_free_fn(pd)
elv_iosched_store
elevator_switch
...
iterate blkg list
blkg_get(blkg) // blkg->refcnt=0->1
list_del_init(&blkg->q_node)
blkg_put(pinned_blkg) // blkg->refcnt=1->0
blkg_release // call_rcu again
rcu_accelerate_cbs // uaf
Fix this by checking hlist_unhashed(&blkg->blkcg_node) before getting
a reference to the blkg. This is the same check used in blkg_destroy()
to detect if a blkg has already been destroyed. If the blkg is already
unhashed, skip processing it since it's being destroyed.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"block/blk-cgroup.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "b5dae1cd0d8368b4338430ff93403df67f0b8bcc",
"status": "affected",
"version": "81c1188905f88b77743d1fdeeedfc8cb7b67787d",
"versionType": "git"
},
{
"lessThan": "083b58373463a6e5ee60ecb135269348f68ad7df",
"status": "affected",
"version": "bfe46d2efe46c5c952f982e2ca94fe2ec5e58e2a",
"versionType": "git"
},
{
"lessThan": "1a267295b1ea6a6477963f3fda84adfecd48fcad",
"status": "affected",
"version": "f1c006f1c6850c14040f8337753a63119bba39b9",
"versionType": "git"
},
{
"lessThan": "7337d012ca3fc3a6a2d1c8e2a19c6d97c38b410d",
"status": "affected",
"version": "f1c006f1c6850c14040f8337753a63119bba39b9",
"versionType": "git"
},
{
"lessThan": "3d8c3da95c75a4d312e272fc7b4076dd3ba9115c",
"status": "affected",
"version": "f1c006f1c6850c14040f8337753a63119bba39b9",
"versionType": "git"
},
{
"lessThan": "d8c872901e6459339374e9eea80aa919176c2ccd",
"status": "affected",
"version": "f1c006f1c6850c14040f8337753a63119bba39b9",
"versionType": "git"
},
{
"lessThan": "5e9220389920f33b6a804d50c548cd0cd1b04634",
"status": "affected",
"version": "f1c006f1c6850c14040f8337753a63119bba39b9",
"versionType": "git"
},
{
"lessThan": "6.1.17",
"status": "affected",
"version": "6.1.16",
"versionType": "semver"
},
{
"lessThan": "6.2.4",
"status": "affected",
"version": "6.2.3",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"block/blk-cgroup.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.3"
},
{
"lessThan": "6.3",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.17",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.2.*",
"status": "unaffected",
"version": "6.2.4",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.157",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.110",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.52",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.2.*",
"status": "unaffected",
"version": "7.2.6",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.3-rc1",
"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\nblk-cgroup: skip dying blkg in blkcg_activate_policy()\n\nWhen switching IO schedulers on a block device, blkcg_activate_policy()\ncan race with concurrent blkcg deletion, leading to a use-after-free in\nrcu_accelerate_cbs.\n\nT1: T2:\n blkg_destroy\n kill(\u0026blkg-\u003erefcnt) // blkg-\u003erefcnt=1-\u003e0\n blkg_release // call_rcu(__blkg_release)\n ...\n blkg_free_workfn\n -\u003epd_free_fn(pd)\nelv_iosched_store\nelevator_switch\n...\niterate blkg list\nblkg_get(blkg) // blkg-\u003erefcnt=0-\u003e1\n list_del_init(\u0026blkg-\u003eq_node)\nblkg_put(pinned_blkg) // blkg-\u003erefcnt=1-\u003e0\nblkg_release // call_rcu again\nrcu_accelerate_cbs // uaf\n\nFix this by checking hlist_unhashed(\u0026blkg-\u003eblkcg_node) before getting\na reference to the blkg. This is the same check used in blkg_destroy()\nto detect if a blkg has already been destroyed. If the blkg is already\nunhashed, skip processing it since it\u0027s being destroyed."
}
],
"id": "CVE-2026-90325",
"lastModified": "2026-09-18T18:17:53.960",
"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"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-09-17T17:17:30.540",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/083b58373463a6e5ee60ecb135269348f68ad7df"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/1a267295b1ea6a6477963f3fda84adfecd48fcad"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3d8c3da95c75a4d312e272fc7b4076dd3ba9115c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/5e9220389920f33b6a804d50c548cd0cd1b04634"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/7337d012ca3fc3a6a2d1c8e2a19c6d97c38b410d"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/b5dae1cd0d8368b4338430ff93403df67f0b8bcc"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/d8c872901e6459339374e9eea80aa919176c2ccd"
}
],
"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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