CVE-2025-39706

Kernel hang via premature KFD debugfs teardown

Published Sep 5, 2025 · Updated May 12, 2026

NULL pointer dereference in Linux KFD debugfs teardown allows local users to hang affected Linux kernels and SIMATIC CN 4100 devices. kfd_process_destroy_wq calls kfd_debugfs_remove_process after kfd_debugfs_fini removes /sys/kernel/debug/kfd, causing debugfs_remove_recursive to dereference a removed hierarchy. Low-privileged local access and the AMD KFD path are required; the demonstrated consequence is a kernel hang, with no reported data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Linux KFD debugfs teardown allows local users to hang affected Linux kernels and SIMATIC CN 4100 devices. kfd_process_destroy_wq calls kfd_debugfs_remove_process after kfd_debugfs_fini removes /sys/kernel/debug/kfd, causing debugfs_remove_recursive to dereference a removed hierarchy. Low-privileged local access and the AMD KFD path are required; the demonstrated consequence is a kernel hang, with no reported data disclosure or modification.

The record

CVE
CVE-2025-39706
Published
Sep 5, 2025
Updated
May 12, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-476, CWE-20, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 5, 2025CVE publishedPublication date reported by the CVE source.
  2. May 12, 2026Record 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=3.19
  2. Affected versionversion=4a488a7ad71401169cecee75dc94bcce642e2c53 <2e58401a24e7b2d4ec619104e1a76590c1284a4c
  3. Affected versionversion=4a488a7ad71401169cecee75dc94bcce642e2c53 <74ee7445c3b61c3bd899a54bd82c1982cb3a8206
  4. Affected versionversion=4a488a7ad71401169cecee75dc94bcce642e2c53 <910735ded17cc306625e7e1cdcc8102f7ac60994
  5. Affected versionversion=4a488a7ad71401169cecee75dc94bcce642e2c53 <96609a51e6134542bf90e053c2cd2fe4f61ebce3
  6. Affected versionversion=4a488a7ad71401169cecee75dc94bcce642e2c53 <fc35c955da799ba62f6f977d58e0866d0251e3f8

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=3.19; version=4a488a7ad71401169cecee75dc94bcce642e2c53 <2e58401a24e7b2d4ec619104e1a76590c1284a4c; version=4a488a7ad71401169cecee75dc94bcce642e2c53 <74ee7445c3b61c3bd899a54bd82c1982cb3a8206; version=4a488a7ad71401169cecee75dc94bcce642e2c53 <910735ded17cc306625e7e1cdcc8102f7ac60994; version=4a488a7ad71401169cecee75dc94bcce642e2c53 <96609a51e6134542bf90e053c2cd2fe4f61ebce3; version=4a488a7ad71401169cecee75dc94bcce642e2c53 <fc35c955da799ba62f6f977d58e0866d0251e3f8
Siemens · SIMATIC CN 4100version=0 <V5.0

Published CVSS scores

5.5Siemens ProductCERTCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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-476NULL Pointer Dereference
CWE-20Improper Input Validation
T1499.004Application or System Exploitation

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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