CVE-2026-19940
The Bluetooth Classic Hands-Free Profile Audio Gateway implementation in subsys/bluetooth/host/classic/hfp_ag.c keeps its struct bt_hfp_ag objects in a static pool indexed by ACL connection index. On link teardown, hfp_ag_disconnected() cancels ag->tx_work and the per-call work items and then clears ag->acl_conn, which marks the pool slot as free — but it leaves ag->ongoing_call_work (and ag->slc_work) untouched.
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The next connection that lands on the same slot enters hfp_ag_create(), whose only occupancy test is ag->acl_conn, and immediately executes memset(ag, 0, sizeof(struct bt_hfp_ag)) followed by k_work_init_delayable(). Zeroing and re-initialising a k_work_delayable whose struct _timeout node is still linked into the kernel timeout list leaves the kernel holding a reference to a node with NULL prev/next links.
ag->ongoing_call_work is armed by the remote peer: when a Hands-Free unit sends AT+CIND? during Service Level Connection establishment and the application provides the asynchronous get_ongoing_call callback, the AG schedules the work for CONFIG_BT_HFP_AG_GET_ONGOING_CALL_TIMEOUT milliseconds (default 10000). The timer is cancelled only if the application answers in time via bt_hfp_ag_ongoing_calls(). A peer that sends AT+CIND?, then disconnects the HFP RFCOMM DLC, then immediately re-opens it on the same ACL link, reuses the same pool slot deterministically while the timeout is still pending — the AG's RFCOMM server accept path (hfp_ag_accept()) calls hfp_ag_create() directly, so the remote side drives both teardown and re-creation.
The result is corruption of the kernel's timeout list: sys_dlist_remove() on the zeroed node performs writes through NULL pointers from the clock-announce path, and rescheduling the re-initialised work re-inserts a node the list already references, creating a cycle that the announce loop walks with interrupts locked. The observable impact is a fault or hang of the whole system, i.e. a denial of service reachable from Bluetooth radio range; no attacker-controlled data is written, so this does not by itself yield code execution. Exposure is limited to builds with CONFIG_BT_HFP_AG (marked experimental and disabled by default) whose application implements the asynchronous get_ongoing_call callback.
CVSS
- Base score
- 6.5
- Version
- 3.1
- Vector
- CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days
- 0.19 %
- Percentile among all scored CVEs
- 8
- Score date
- 10/20/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
ATT&CK techniques
How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.
- Exploitation
T1210Exploitation of Remote Serviceslateral movement90 % - Primary impact
T1499Endpoint Denial of Serviceimpact88 %
Vector AV:A/PR:N/UI:N (adyacente, alcance por radio Bluetooth) → T1210; el texto describe corrupción de la lista de timeouts del kernel que provoca fallo o cuelgue del sistema (DoS).
Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.
ATT&CK mitigations that cover these techniques
Affected technologies (1)
⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.
CWEs
- CWE-416
References
Raw JSON (NVD)
Show
{
"id": "CVE-2026-19940",
"cveTags": [],
"metrics": {
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"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
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"version": "2.0.3",
"timestamp": "2026-10-14T19:26:45.572487Z"
}
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"cvssMetricV31": [
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"baseScore": 6.5,
"attackVector": "ADJACENT_NETWORK",
"baseSeverity": "MEDIUM",
"vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"integrityImpact": "NONE",
"userInteraction": "NONE",
"attackComplexity": "LOW",
"availabilityImpact": "HIGH",
"privilegesRequired": "NONE",
"confidentialityImpact": "NONE"
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"impactScore": 3.6,
"exploitabilityScore": 2.8
}
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"affected": [
{
"source": "vulnerabilities@zephyrproject.org",
"affectedData": [
{
"vendor": "zephyrproject",
"product": "zephyr",
"versions": [
{
"status": "affected",
"version": "4.2.0",
"versionType": "semver",
"lessThanOrEqual": "4.4.2"
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],
"packageName": "zephyr",
"programFiles": [
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],
"collectionURL": "https://github.com/zephyrproject-rtos/zephyr",
"defaultStatus": "unaffected",
"programRoutines": [
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"name": "hfp_ag_create"
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],
"published": "2026-10-13T17:17:40.107",
"references": [
{
"url": "https://github.com/zephyrproject-rtos/zephyr/commit/204c36b896fe8d68ca3cb3d00216f245f91d14be",
"source": "vulnerabilities@zephyrproject.org"
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{
"url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-v47w-8959-rx62",
"source": "vulnerabilities@zephyrproject.org"
}
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"vulnStatus": "Awaiting Analysis",
"weaknesses": [
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"source": "vulnerabilities@zephyrproject.org",
"description": [
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"value": "CWE-416"
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"descriptions": [
{
"lang": "en",
"value": "The Bluetooth Classic Hands-Free Profile Audio Gateway implementation in subsys/bluetooth/host/classic/hfp_ag.c keeps its struct bt_hfp_ag objects in a static pool indexed by ACL connection index. On link teardown, hfp_ag_disconnected() cancels ag->tx_work and the per-call work items and then clears ag->acl_conn, which marks the pool slot as free — but it leaves ag->ongoing_call_work (and ag->slc_work) untouched. The next connection that lands on the same slot enters hfp_ag_create(), whose only occupancy test is ag->acl_conn, and immediately executes memset(ag, 0, sizeof(struct bt_hfp_ag)) followed by k_work_init_delayable(). Zeroing and re-initialising a k_work_delayable whose struct _timeout node is still linked into the kernel timeout list leaves the kernel holding a reference to a node with NULL prev/next links.\n\nag->ongoing_call_work is armed by the remote peer: when a Hands-Free unit sends AT+CIND? during Service Level Connection establishment and the application provides the asynchronous get_ongoing_call callback, the AG schedules the work for CONFIG_BT_HFP_AG_GET_ONGOING_CALL_TIMEOUT milliseconds (default 10000). The timer is cancelled only if the application answers in time via bt_hfp_ag_ongoing_calls(). A peer that sends AT+CIND?, then disconnects the HFP RFCOMM DLC, then immediately re-opens it on the same ACL link, reuses the same pool slot deterministically while the timeout is still pending — the AG's RFCOMM server accept path (hfp_ag_accept()) calls hfp_ag_create() directly, so the remote side drives both teardown and re-creation.\n\nThe result is corruption of the kernel's timeout list: sys_dlist_remove() on the zeroed node performs writes through NULL pointers from the clock-announce path, and rescheduling the re-initialised work re-inserts a node the list already references, creating a cycle that the announce loop walks with interrupts locked. The observable impact is a fault or hang of the whole system, i.e. a denial of service reachable from Bluetooth radio range; no attacker-controlled data is written, so this does not by itself yield code execution. Exposure is limited to builds with CONFIG_BT_HFP_AG (marked experimental and disabled by default) whose application implements the asynchronous get_ongoing_call callback."
}
],
"lastModified": "2026-10-14T20:17:35.800",
"sourceIdentifier": "vulnerabilities@zephyrproject.org"
}