CVE-2025-39863

Local kernel compromise via btcoex timer race

Published Sep 19, 2025 · Updated Sep 19, 2025

Use-after-free in Linux brcmfmac allows local users to read or corrupt kernel memory and crash the system through a timer race. brcmf_btcoex_detach() conditionally skips timer shutdown after brcmf_btcoex_timerfunc() clears timer_on, allowing the callback to queue work after cancellation and free. Exploitation requires local CAP_NET_ADMIN access to a Broadcom wireless device plus a concurrent driver teardown or bus-reset path; no remote frame directly triggers both sides.

CVSS severity7.8
High
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux brcmfmac allows local users to read or corrupt kernel memory and crash the system through a timer race. brcmf_btcoex_detach() conditionally skips timer shutdown after brcmf_btcoex_timerfunc() clears timer_on, allowing the callback to queue work after cancellation and free. Exploitation requires local CAP_NET_ADMIN access to a Broadcom wireless device plus a concurrent driver teardown or bus-reset path; no remote frame directly triggers both sides.

The record

CVE
CVE-2025-39863
Published
Sep 19, 2025
Updated
Sep 19, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 19, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 19, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=3.10
  2. Affected versionversion=61730d4dfffc2cc9d3a49fad87633008105c18ba <2f6fbc8e04ca1d1d5c560be694199f847229c625
  3. Affected versionversion=61730d4dfffc2cc9d3a49fad87633008105c18ba <3e789f8475f6c857c88de5c5bf4b24b11a477dd7
  4. Affected versionversion=61730d4dfffc2cc9d3a49fad87633008105c18ba <9cb83d4be0b9b697eae93d321e0da999f9cdfcfc
  5. Affected versionversion=61730d4dfffc2cc9d3a49fad87633008105c18ba <f1150153c4e5940fe49ab51136343c5b4fe49d63

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.10; version=61730d4dfffc2cc9d3a49fad87633008105c18ba <2f6fbc8e04ca1d1d5c560be694199f847229c625; version=61730d4dfffc2cc9d3a49fad87633008105c18ba <3e789f8475f6c857c88de5c5bf4b24b11a477dd7; version=61730d4dfffc2cc9d3a49fad87633008105c18ba <9cb83d4be0b9b697eae93d321e0da999f9cdfcfc; version=61730d4dfffc2cc9d3a49fad87633008105c18ba <f1150153c4e5940fe49ab51136343c5b4fe49d63

Published CVSS scores

7.8Linux Kernel CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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