CVE-2026-74540 (GCVE-0-2026-74540)
Vulnerability from cvelistv5
Published
2026-08-15 12:27
Modified
2026-08-19 16:38
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp
l2cap_le_connect_rsp() obtains a channel via
__l2cap_get_chan_by_ident() but neither holds a reference nor uses
l2cap_chan_hold_unless_zero() before locking and operating on it.
A concurrent l2cap_chan_del() triggered by a remote disconnect can
free the channel between the lookup and l2cap_chan_lock(), causing
a use-after-free.
The BR/EDR counterpart l2cap_connect_rsp() and the sibling handler
l2cap_le_command_rej() already use l2cap_chan_hold_unless_zero()
to safely hold a reference, but l2cap_le_connect_rsp() was left
unprotected.
Fix by adding l2cap_chan_hold_unless_zero() after the ident lookup
and l2cap_chan_put() on the exit path, consistent with other L2CAP
response handlers.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: f1496dee9cbde2a62821f4441dadb0d3360f60c3 Version: f1496dee9cbde2a62821f4441dadb0d3360f60c3 Version: f1496dee9cbde2a62821f4441dadb0d3360f60c3 Version: f1496dee9cbde2a62821f4441dadb0d3360f60c3 Version: f1496dee9cbde2a62821f4441dadb0d3360f60c3 Version: f1496dee9cbde2a62821f4441dadb0d3360f60c3 Version: f1496dee9cbde2a62821f4441dadb0d3360f60c3 Version: f1496dee9cbde2a62821f4441dadb0d3360f60c3 |
||
{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/bluetooth/l2cap_core.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"version": "f1496dee9cbde2a62821f4441dadb0d3360f60c3",
"versionType": "git"
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{
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],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "3.14"
},
{
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"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.265",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.216",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.183",
"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"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
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"versionEndExcluding": "5.10.265",
"versionStartIncluding": "3.14",
"vulnerable": true
},
{
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{
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{
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"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp\n\nl2cap_le_connect_rsp() obtains a channel via\n__l2cap_get_chan_by_ident() but neither holds a reference nor uses\nl2cap_chan_hold_unless_zero() before locking and operating on it.\nA concurrent l2cap_chan_del() triggered by a remote disconnect can\nfree the channel between the lookup and l2cap_chan_lock(), causing\na use-after-free.\n\nThe BR/EDR counterpart l2cap_connect_rsp() and the sibling handler\nl2cap_le_command_rej() already use l2cap_chan_hold_unless_zero()\nto safely hold a reference, but l2cap_le_connect_rsp() was left\nunprotected.\n\nFix by adding l2cap_chan_hold_unless_zero() after the ident lookup\nand l2cap_chan_put() on the exit path, consistent with other L2CAP\nresponse handlers."
}
],
"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 vulnerability is reached when the kernel processes an incoming L2CAP LE Connect Response over an established Bluetooth LE ACL link (HCI ACL receive \u2192 l2cap_recv_acldata \u2192 l2cap_le_sig_channel \u2192 l2cap_le_connect_rsp), requiring radio proximity rather than routable Internet access.\nAC:L - The remote Bluetooth peer controls both sides of the race by sending L2CAP_LE_CONN_RSP while concurrently triggering channel teardown via L2CAP DISCONN_REQ or HCI disconnect, freeing the channel between __l2cap_get_chan_by_ident() and l2cap_chan_lock() without attacker-uncontrollable timing.\nPR:N - No local privileges on the victim are required; exploitation needs only a nearby attacker with an established LE Bluetooth connection sending crafted L2CAP signaling packets, with no root, CAP_NET_ADMIN, or user-namespace capability on the target host.\nUI:N - On phones, wearables, automotive, and IoT deployments, paired or background Bluetooth clients routinely auto-initiate L2CAP credit-based connections without per-attack user confirmation once an LE link is up, enabling trigger of the pending outgoing connect path.\nS:U - Impact is confined to kernel memory and privileges on the Bluetooth-connected host; there is no VM guest-to-host escape, sandbox breakout, or IOMMU/DMA boundary crossing, so security scope remains unchanged per kernel CVSS guidance.\nC:H - Use-after-free of heap-allocated struct l2cap_chan allows attacker-controlled reuse of freed slab memory, enabling disclosure of kernel heap contents and pointers through corrupted channel fields accessed after premature free.\nI:H - The UAF window writes channel state (ident, dcid, mtu, credits) and invokes chan-\u003eops function pointers (ready, teardown) on freed memory, enabling heap spraying and control-flow hijack for arbitrary kernel code execution.\nA:H - Operating on a freed l2cap_chan can immediately kernel-oops or panic from corrupt mutex/state during lock/unlock and callback dispatch; UAF in softirq L2CAP processing inherently threatens full system availability."
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-19T16:38:32.306Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/15d6c2367217a6a20b1abae9f38ded716bf620f1"
},
{
"url": "https://git.kernel.org/stable/c/1818180fe12d6cec7a437bc59cde8efdf6b10250"
},
{
"url": "https://git.kernel.org/stable/c/8325eafb38c3dee5af329266393763693d17381b"
},
{
"url": "https://git.kernel.org/stable/c/fd4c1e301bdec60a40728ea37de531cbccda501a"
},
{
"url": "https://git.kernel.org/stable/c/522b730c62c53a1981604fd73524697fd347830d"
},
{
"url": "https://git.kernel.org/stable/c/58e3c5289ad230a7e24ae4b0c7b43f5ee6e32136"
},
{
"url": "https://git.kernel.org/stable/c/09f447accc2570751e7d17f0dc0788b40d3edade"
},
{
"url": "https://git.kernel.org/stable/c/c4740e7f23ff9a8210198d8b4703259e21b9f69d"
}
],
"title": "Bluetooth: L2CAP: fix UAF in l2cap_le_connect_rsp",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-74540",
"datePublished": "2026-08-15T12:27:51.522Z",
"dateReserved": "2026-08-15T05:44:03.913Z",
"dateUpdated": "2026-08-19T16:38:32.306Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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