CVE-2026-74534 (GCVE-0-2026-74534)
Vulnerability from cvelistv5 – Published: 2026-08-15 12:27 – Updated: 2026-08-17 05:48
VLAI
EPSS
VEX
Title
Bluetooth: ISO: fix refcounting of iso_conn
Summary
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: ISO: fix refcounting of iso_conn
iso_conn_del() and iso_chan_del() have a race that results to double-put
of iso_conn:
[Task hdev->workqueue] [Task 2]
iso_conn_del iso_chan_del
iso_conn_hold_unless_zero iso_conn_lock
iso_conn_lock conn->sk = NULL
iso_conn_unlock
sk = iso_sock_hold(conn) <---------´
if (!sk) iso_conn_put iso_conn_put
iso_conn_put /* UAF */
The extra put for !sk in iso_conn_del() is currently required since
failing iso_chan_add() may leave iso_conn not associated with any sk.
Fix by having iso_pi(sk)->conn own refcount when non-NULL, so
iso_conn_del does not need to put it. Adjust the iso_conn_add()
refcounting so that conn is put if it does not get associated with an
sk.
Severity
8.8 (High)
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
dc26097bdb864a0d5955b9a25e43376ffc1af99b , < 3b921533e8aa95b77aadcf31737595578e735f3c
(git)
Affected: dc26097bdb864a0d5955b9a25e43376ffc1af99b , < 8208b4939afb0a1977fffe902c3ca42fe0f3baaa (git) Affected: dc26097bdb864a0d5955b9a25e43376ffc1af99b , < fdfde532ab1caa165fcd8985001157ac8b4db365 (git) Affected: f53e7489273dc2bb307bf50f319b3762d45534f0 (git) Affected: a58d0f5dac322e16cc75334d000666512341bde5 (git) Affected: 6.11.11 , < 6.12 (semver) Affected: 6.12.2 , < 6.13 (semver) |
guessed | |
| Linux | Linux |
Affected:
6.13
Unaffected: 0 , < 6.13 (semver) Unaffected: 6.18.44 , ≤ 6.18.* (semver) Unaffected: 7.1.8 , ≤ 7.1.* (semver) Unaffected: 7.2 , ≤ * (original_commit_for_fix) |
guessed |
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/bluetooth/iso.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "3b921533e8aa95b77aadcf31737595578e735f3c",
"status": "affected",
"version": "dc26097bdb864a0d5955b9a25e43376ffc1af99b",
"versionType": "git"
},
{
"lessThan": "8208b4939afb0a1977fffe902c3ca42fe0f3baaa",
"status": "affected",
"version": "dc26097bdb864a0d5955b9a25e43376ffc1af99b",
"versionType": "git"
},
{
"lessThan": "fdfde532ab1caa165fcd8985001157ac8b4db365",
"status": "affected",
"version": "dc26097bdb864a0d5955b9a25e43376ffc1af99b",
"versionType": "git"
},
{
"status": "affected",
"version": "f53e7489273dc2bb307bf50f319b3762d45534f0",
"versionType": "git"
},
{
"status": "affected",
"version": "a58d0f5dac322e16cc75334d000666512341bde5",
"versionType": "git"
},
{
"lessThan": "6.12",
"status": "affected",
"version": "6.11.11",
"versionType": "semver"
},
{
"lessThan": "6.13",
"status": "affected",
"version": "6.12.2",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/bluetooth/iso.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.13"
},
{
"lessThan": "6.13",
"status": "unaffected",
"version": "0",
"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"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.44",
"versionStartIncluding": "6.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1.8",
"versionStartIncluding": "6.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.2",
"versionStartIncluding": "6.13",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.11.11",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionStartIncluding": "6.12.2",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: ISO: fix refcounting of iso_conn\n\niso_conn_del() and iso_chan_del() have a race that results to double-put\nof iso_conn:\n\n [Task hdev-\u003eworkqueue] [Task 2]\n iso_conn_del iso_chan_del\n iso_conn_hold_unless_zero iso_conn_lock\n iso_conn_lock conn-\u003esk = NULL\n iso_conn_unlock\n sk = iso_sock_hold(conn) \u003c---------\u00b4\n if (!sk) iso_conn_put iso_conn_put\n iso_conn_put /* UAF */\n\nThe extra put for !sk in iso_conn_del() is currently required since\nfailing iso_chan_add() may leave iso_conn not associated with any sk.\n\nFix by having iso_pi(sk)-\u003econn own refcount when non-NULL, so\niso_conn_del does not need to put it. Adjust the iso_conn_add()\nrefcounting so that conn is put if it does not get associated with an\nsk."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 8.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"value": "AV:A - The bug is in Bluetooth ISO connection teardown; a remote LE Audio/CIS/BIS peer in range can trigger iso_conn_del via HCI disconnect events (iso_disconn_cfm) that race with concurrent socket teardown.\nAC:L - The double kref_put race is between iso_conn_del and iso_chan_del; an adjacent attacker controls disconnect timing and can repeatedly connect/disconnect to race automatic kernel and Bluetooth daemon socket cleanup.\nPR:N - No local UNIX privileges are required; a malicious or compromised adjacent Bluetooth ISO peer with an established connection can initiate the disconnect leg without root, capabilities, or user-namespace admin rights.\nUI:N - No explicit victim action is needed beyond an active ISO session; remote disconnect triggers automatic HCI teardown and stack socket close that can race iso_chan_del without the user manually closing applications.\nS:U - The vulnerability corrupts kernel heap lifetime of iso_conn objects within the Bluetooth subsystem and does not cross VM, hypervisor, or IOMMU security boundaries.\nC:H - Premature kfree of iso_conn from the refcount race is a use-after-free that can expose kernel heap contents and be leveraged for arbitrary kernel memory disclosure.\nI:H - UAF on iso_conn enables heap grooming and corrupted pointer dereferences that can be leveraged for arbitrary kernel memory writes or privilege-escalating code execution.\nA:H - The double iso_conn_put can free iso_conn while still referenced, causing kernel oops/panic or reliably exploitable instability during ISO connection teardown."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-17T05:48:23.337Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/3b921533e8aa95b77aadcf31737595578e735f3c"
},
{
"url": "https://git.kernel.org/stable/c/8208b4939afb0a1977fffe902c3ca42fe0f3baaa"
},
{
"url": "https://git.kernel.org/stable/c/fdfde532ab1caa165fcd8985001157ac8b4db365"
}
],
"title": "Bluetooth: ISO: fix refcounting of iso_conn",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74534",
"datePublished": "2026-08-15T12:27:47.831Z",
"dateReserved": "2026-08-15T05:44:03.913Z",
"dateUpdated": "2026-08-17T05:48:23.337Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-74534",
"date": "2026-10-02",
"epss": "0.00375",
"percentile": "0.29121"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/bluetooth/iso.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "3b921533e8aa95b77aadcf31737595578e735f3c",
"status": "affected",
"version": "dc26097bdb864a0d5955b9a25e43376ffc1af99b",
"versionType": "git"
},
{
"lessThan": "8208b4939afb0a1977fffe902c3ca42fe0f3baaa",
"status": "affected",
"version": "dc26097bdb864a0d5955b9a25e43376ffc1af99b",
"versionType": "git"
},
{
"lessThan": "fdfde532ab1caa165fcd8985001157ac8b4db365",
"status": "affected",
"version": "dc26097bdb864a0d5955b9a25e43376ffc1af99b",
"versionType": "git"
},
{
"status": "affected",
"version": "f53e7489273dc2bb307bf50f319b3762d45534f0",
"versionType": "git"
},
{
"status": "affected",
"version": "a58d0f5dac322e16cc75334d000666512341bde5",
"versionType": "git"
},
{
"lessThan": "6.12",
"status": "affected",
"version": "6.11.11",
"versionType": "semver"
},
{
"lessThan": "6.13",
"status": "affected",
"version": "6.12.2",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/bluetooth/iso.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.13"
},
{
"lessThan": "6.13",
"status": "unaffected",
"version": "0",
"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\nBluetooth: ISO: fix refcounting of iso_conn\n\niso_conn_del() and iso_chan_del() have a race that results to double-put\nof iso_conn:\n\n [Task hdev-\u003eworkqueue] [Task 2]\n iso_conn_del iso_chan_del\n iso_conn_hold_unless_zero iso_conn_lock\n iso_conn_lock conn-\u003esk = NULL\n iso_conn_unlock\n sk = iso_sock_hold(conn) \u003c---------\u00b4\n if (!sk) iso_conn_put iso_conn_put\n iso_conn_put /* UAF */\n\nThe extra put for !sk in iso_conn_del() is currently required since\nfailing iso_chan_add() may leave iso_conn not associated with any sk.\n\nFix by having iso_pi(sk)-\u003econn own refcount when non-NULL, so\niso_conn_del does not need to put it. Adjust the iso_conn_add()\nrefcounting so that conn is put if it does not get associated with an\nsk."
}
],
"id": "CVE-2026-74534",
"lastModified": "2026-08-17T06:19:50.400",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "ADJACENT_NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 8.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-08-15T13:17:58.700",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3b921533e8aa95b77aadcf31737595578e735f3c"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/8208b4939afb0a1977fffe902c3ca42fe0f3baaa"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/fdfde532ab1caa165fcd8985001157ac8b4db365"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
},
"redhat_vex": {
"aggregate_severity": "Moderate",
"current_release_date": "2026-08-21T11:33:17+00:00",
"cve": "CVE-2026-74534",
"id": "CVE-2026-74534",
"initial_release_date": "2026-08-15T00:00:00+00:00",
"product_status:known_affected": "184",
"product_status:known_not_affected": "90",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: Bluetooth: ISO: fix refcounting of iso_conn",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74534.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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