CVE-2025-39861

Kernel memory access via stale debugfs files

Published Sep 19, 2025 · Updated Sep 19, 2025

Use-after-free in Linux kernel Bluetooth vhci allows local users with root access to access freed kernel memory through stale debugfs files. The vhci_release() path frees vhci_data without first removing force_suspend, force_wakeup, and related files under hdev->debugfs, leaving their callbacks backed by released storage. The gap before hci_release_dev() removes the directory permits privileged accesses that can trigger invalid kernel-memory use and a system crash.

CVSS severity7.8
High
EPSS probability0.15%
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 kernel Bluetooth vhci allows local users with root access to access freed kernel memory through stale debugfs files. The vhci_release() path frees vhci_data without first removing force_suspend, force_wakeup, and related files under hdev->debugfs, leaving their callbacks backed by released storage. The gap before hci_release_dev() removes the directory permits privileged accesses that can trigger invalid kernel-memory use and a system crash.

The record

CVE
CVE-2025-39861
Published
Sep 19, 2025
Updated
Sep 19, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-416
Attack vector
local
Privileges
admin

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=6.4
  2. Affected versionversion=ab4e4380d4e158486e595013a2635190e07e28ce <1503756fffe76d5aea2371a4b8dee20c3577bcfd
  3. Affected versionversion=ab4e4380d4e158486e595013a2635190e07e28ce <28010791193a4503f054e8d69a950ef815deb539
  4. Affected versionversion=ab4e4380d4e158486e595013a2635190e07e28ce <7cc08f2f127b9a66f46ea918e34353811a7cb378
  5. Affected versionversion=ab4e4380d4e158486e595013a2635190e07e28ce <bd75eba88e88d7b896b0c737b02a74a12afc235f

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linuxversion=6.4; version=ab4e4380d4e158486e595013a2635190e07e28ce <1503756fffe76d5aea2371a4b8dee20c3577bcfd; version=ab4e4380d4e158486e595013a2635190e07e28ce <28010791193a4503f054e8d69a950ef815deb539; version=ab4e4380d4e158486e595013a2635190e07e28ce <7cc08f2f127b9a66f46ea918e34353811a7cb378; version=ab4e4380d4e158486e595013a2635190e07e28ce <bd75eba88e88d7b896b0c737b02a74a12afc235f

Published CVSS scores

7.8CISA ADPCVSS: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
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free

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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