CVE-2025-39701

Firmware-update denial via incorrect version comparison

Published Sep 5, 2025 · Updated May 12, 2026

Improper version validation in affected Linux branches from 5.17 and SIMATIC CN 4100 before V5.0 allows local users to block driver updates. The applicable_image function compares an update binary's runtime version with drv_rt_version instead of comparing its security version with drv_svn. A binary with a lower runtime version is falsely rejected, interrupting only the update operation; no disclosure or code execution is reported.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper version validation in affected Linux branches from 5.17 and SIMATIC CN 4100 before V5.0 allows local users to block driver updates. The applicable_image function compares an update binary's runtime version with drv_rt_version instead of comparing its security version with drv_svn. A binary with a lower runtime version is falsely rejected, interrupting only the update operation; no disclosure or code execution is reported.

The record

CVE
CVE-2025-39701
Published
Sep 5, 2025
Updated
May 12, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-1025
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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=0db89fa243e5edc5de38c88b369e4c3755c5fb74 <79300ff532bccbbf654992c7c0863b49a6c3973c
  2. Affected versionversion=0db89fa243e5edc5de38c88b369e4c3755c5fb74 <8151320c747efb22d30b035af989fed0d502176e
  3. Affected versionversion=0db89fa243e5edc5de38c88b369e4c3755c5fb74 <908094681f645d3a78e18ef90561a97029e2df7b
  4. Affected versionversion=0db89fa243e5edc5de38c88b369e4c3755c5fb74 <b00219888c11519ef75d988fa8a780da68ff568e
  5. Affected versionversion=0db89fa243e5edc5de38c88b369e4c3755c5fb74 <cf0a88124e357bffda487cbf3cb612bb97eb97e4
  6. Affected versionversion=5.17

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=0db89fa243e5edc5de38c88b369e4c3755c5fb74 <79300ff532bccbbf654992c7c0863b49a6c3973c; version=0db89fa243e5edc5de38c88b369e4c3755c5fb74 <8151320c747efb22d30b035af989fed0d502176e; version=0db89fa243e5edc5de38c88b369e4c3755c5fb74 <908094681f645d3a78e18ef90561a97029e2df7b; version=0db89fa243e5edc5de38c88b369e4c3755c5fb74 <b00219888c11519ef75d988fa8a780da68ff568e; version=0db89fa243e5edc5de38c88b369e4c3755c5fb74 <cf0a88124e357bffda487cbf3cb612bb97eb97e4; version=5.17
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

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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-1025Comparison Using Wrong Factors

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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