CVE-2025-39863 (GCVE-0-2025-39863)
Vulnerability from cvelistv5 – Published: 2025-09-19 15:26 – Updated: 2026-08-05 12:05
VLAI
EPSS
VEX
Title
wifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work
Summary
In the Linux kernel, the following vulnerability has been resolved:
wifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work
The brcmf_btcoex_detach() only shuts down the btcoex timer, if the
flag timer_on is false. However, the brcmf_btcoex_timerfunc(), which
runs as timer handler, sets timer_on to false. This creates critical
race conditions:
1.If brcmf_btcoex_detach() is called while brcmf_btcoex_timerfunc()
is executing, it may observe timer_on as false and skip the call to
timer_shutdown_sync().
2.The brcmf_btcoex_timerfunc() may then reschedule the brcmf_btcoex_info
worker after the cancel_work_sync() has been executed, resulting in
use-after-free bugs.
The use-after-free bugs occur in two distinct scenarios, depending on
the timing of when the brcmf_btcoex_info struct is freed relative to
the execution of its worker thread.
Scenario 1: Freed before the worker is scheduled
The brcmf_btcoex_info is deallocated before the worker is scheduled.
A race condition can occur when schedule_work(&bt_local->work) is
called after the target memory has been freed. The sequence of events
is detailed below:
CPU0 | CPU1
brcmf_btcoex_detach | brcmf_btcoex_timerfunc
| bt_local->timer_on = false;
if (cfg->btcoex->timer_on) |
... |
cancel_work_sync(); |
... |
kfree(cfg->btcoex); // FREE |
| schedule_work(&bt_local->work); // USE
Scenario 2: Freed after the worker is scheduled
The brcmf_btcoex_info is freed after the worker has been scheduled
but before or during its execution. In this case, statements within
the brcmf_btcoex_handler() — such as the container_of macro and
subsequent dereferences of the brcmf_btcoex_info object will cause
a use-after-free access. The following timeline illustrates this
scenario:
CPU0 | CPU1
brcmf_btcoex_detach | brcmf_btcoex_timerfunc
| bt_local->timer_on = false;
if (cfg->btcoex->timer_on) |
... |
cancel_work_sync(); |
... | schedule_work(); // Reschedule
|
kfree(cfg->btcoex); // FREE | brcmf_btcoex_handler() // Worker
/* | btci = container_of(....); // USE
The kfree() above could | ...
also occur at any point | btci-> // USE
during the worker's execution|
*/ |
To resolve the race conditions, drop the conditional check and call
timer_shutdown_sync() directly. It can deactivate the timer reliably,
regardless of its current state. Once stopped, the timer_on state is
then set to false.
Severity
7.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-01-14 19:23 UTC
CWE
- CWE-416 - Use After Free
Assigner
References
6 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
61730d4dfffc2cc9d3a49fad87633008105c18ba , < c75600e69e66a751cc046cd9c407b942f298d852
(git)
Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < ae58f70bde0433f27ef4b388ab50634736607bf6 (git) Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < f1150153c4e5940fe49ab51136343c5b4fe49d63 (git) Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < 3e789f8475f6c857c88de5c5bf4b24b11a477dd7 (git) Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < 2f6fbc8e04ca1d1d5c560be694199f847229c625 (git) Affected: 61730d4dfffc2cc9d3a49fad87633008105c18ba , < 9cb83d4be0b9b697eae93d321e0da999f9cdfcfc (git) |
guessed | |
| Linux | Linux |
Affected:
3.10
Unaffected: 0 , < 3.10 (semver) Unaffected: 5.15.210 , ≤ 5.15.* (semver) Unaffected: 6.1.167 , ≤ 6.1.* (semver) Unaffected: 6.6.105 , ≤ 6.6.* (semver) Unaffected: 6.12.46 , ≤ 6.12.* (semver) Unaffected: 6.16.6 , ≤ 6.16.* (semver) Unaffected: 6.17 , ≤ * (original_commit_for_fix) |
guessed |
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work\n\nThe brcmf_btcoex_detach() only shuts down the btcoex timer, if the\nflag timer_on is false. However, the brcmf_btcoex_timerfunc(), which\nruns as timer handler, sets timer_on to false. This creates critical\nrace conditions:\n\n1.If brcmf_btcoex_detach() is called while brcmf_btcoex_timerfunc()\nis executing, it may observe timer_on as false and skip the call to\ntimer_shutdown_sync().\n\n2.The brcmf_btcoex_timerfunc() may then reschedule the brcmf_btcoex_info\nworker after the cancel_work_sync() has been executed, resulting in\nuse-after-free bugs.\n\nThe use-after-free bugs occur in two distinct scenarios, depending on\nthe timing of when the brcmf_btcoex_info struct is freed relative to\nthe execution of its worker thread.\n\nScenario 1: Freed before the worker is scheduled\n\nThe brcmf_btcoex_info is deallocated before the worker is scheduled.\nA race condition can occur when schedule_work(\u0026bt_local-\u003ework) is\ncalled after the target memory has been freed. The sequence of events\nis detailed below:\n\nCPU0 | CPU1\nbrcmf_btcoex_detach | brcmf_btcoex_timerfunc\n | bt_local-\u003etimer_on = false;\n if (cfg-\u003ebtcoex-\u003etimer_on) |\n ... |\n cancel_work_sync(); |\n ... |\n kfree(cfg-\u003ebtcoex); // FREE |\n | schedule_work(\u0026bt_local-\u003ework); // USE\n\nScenario 2: Freed after the worker is scheduled\n\nThe brcmf_btcoex_info is freed after the worker has been scheduled\nbut before or during its execution. In this case, statements within\nthe brcmf_btcoex_handler() \u2014 such as the container_of macro and\nsubsequent dereferences of the brcmf_btcoex_info object will cause\na use-after-free access. The following timeline illustrates this\nscenario:\n\nCPU0 | CPU1\nbrcmf_btcoex_detach | brcmf_btcoex_timerfunc\n | bt_local-\u003etimer_on = false;\n if (cfg-\u003ebtcoex-\u003etimer_on) |\n ... |\n cancel_work_sync(); |\n ... | schedule_work(); // Reschedule\n |\n kfree(cfg-\u003ebtcoex); // FREE | brcmf_btcoex_handler() // Worker\n /* | btci = container_of(....); // USE\n The kfree() above could | ...\n also occur at any point | btci-\u003e // USE\n during the worker\u0027s execution|\n */ |\n\nTo resolve the race conditions, drop the conditional check and call\ntimer_shutdown_sync() directly. It can deactivate the timer reliably,\nregardless of its current state. Once stopped, the timer_on state is\nthen set to false."
}
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"id": "CVE-2025-39863",
"lastModified": "2026-06-19T13:16:22.500",
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"timestamp": "2026-01-14T19:23:53.735650Z",
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"published": "2025-09-19T16:15:45.310",
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{
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Modified",
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"source": "nvd@nist.gov",
"type": "Primary"
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"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"type": "Secondary"
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"redhat_vex": {
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"current_release_date": "2026-06-30T01:23:56+00:00",
"cve": "CVE-2025-39863",
"id": "CVE-2025-39863",
"initial_release_date": "2025-09-19T00:00:00+00:00",
"product_status:known_affected": "260",
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"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: wifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-39863.json",
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},
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"title": "SUSE CVE CVE-2025-39863",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: brcmfmac: fix use-after-free when rescheduling brcmf_btcoex_info work\n\nThe brcmf_btcoex_detach() only shuts down the btcoex timer, if the\nflag timer_on is false. However, the brcmf_btcoex_timerfunc(), which\nruns as timer handler, sets timer_on to false. This creates critical\nrace conditions:\n\n1.If brcmf_btcoex_detach() is called while brcmf_btcoex_timerfunc()\nis executing, it may observe timer_on as false and skip the call to\ntimer_shutdown_sync().\n\n2.The brcmf_btcoex_timerfunc() may then reschedule the brcmf_btcoex_info\nworker after the cancel_work_sync() has been executed, resulting in\nuse-after-free bugs.\n\nThe use-after-free bugs occur in two distinct scenarios, depending on\nthe timing of when the brcmf_btcoex_info struct is freed relative to\nthe execution of its worker thread.\n\nScenario 1: Freed before the worker is scheduled\n\nThe brcmf_btcoex_info is deallocated before the worker is scheduled.\nA race condition can occur when schedule_work(\u0026bt_local-\u003ework) is\ncalled after the target memory has been freed. The sequence of events\nis detailed below:\n\nCPU0 | CPU1\nbrcmf_btcoex_detach | brcmf_btcoex_timerfunc\n | bt_local-\u003etimer_on = false;\n if (cfg-\u003ebtcoex-\u003etimer_on) |\n ... |\n cancel_work_sync(); |\n ... |\n kfree(cfg-\u003ebtcoex); // FREE |\n | schedule_work(\u0026bt_local-\u003ework); // USE\n\nScenario 2: Freed after the worker is scheduled\n\nThe brcmf_btcoex_info is freed after the worker has been scheduled\nbut before or during its execution. In this case, statements within\nthe brcmf_btcoex_handler() \u2014 such as the container_of macro and\nsubsequent dereferences of the brcmf_btcoex_info object will cause\na use-after-free access. The following timeline illustrates this\nscenario:\n\nCPU0 | CPU1\nbrcmf_btcoex_detach | brcmf_btcoex_timerfunc\n | bt_local-\u003etimer_on = false;\n if (cfg-\u003ebtcoex-\u003etimer_on) |\n ... |\n cancel_work_sync(); |\n ... | schedule_work(); // Reschedule\n |\n kfree(cfg-\u003ebtcoex); // FREE | brcmf_btcoex_handler() // Worker\n /* | btci = container_of(....); // USE\n The kfree() above could | ...\n also occur at any point | btci-\u003e // USE\n during the worker\u0027s execution|\n */ |\n\nTo resolve the race conditions, drop the conditional check and call\ntimer_shutdown_sync() directly. It can deactivate the timer reliably,\nregardless of its current state. Once stopped, the timer_on state is\nthen set to false."
}
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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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