CVE-2026-40851

Local code execution via crafted USB file

Published May 27, 2026 · Updated May 27, 2026

Improper input validation in cfgparser in REX 100/200/250 and mbNET.mini allows local users to execute code via crafted USB files. A type-confusion condition occurs while cfgparser processes the configuration, but CERT@VDE does not disclose the exact validation error or parsing operation. Local access to supply prepared USB storage is required; successful execution fully compromises the router firmware.

CVSS severity8.4
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper input validation in cfgparser in REX 100/200/250 and mbNET.mini allows local users to execute code via crafted USB files. A type-confusion condition occurs while cfgparser processes the configuration, but CERT@VDE does not disclose the exact validation error or parsing operation. Local access to supply prepared USB storage is required; successful execution fully compromises the router firmware.

The record

CVE
CVE-2026-40851
Published
May 27, 2026
Updated
May 27, 2026
Vendor
Helmholz GmbH & Co. KG
Product
REX 200/250
Classifications
CWE-1287, T1200
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 27, 2026CVE publishedPublication date reported by the CVE source.
  2. May 27, 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=0.0.0 <=8.4.4
  2. Affected versionversion=8.4.4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Helmholz GmbH & Co. KG · REX 200/250version=0.0.0 <=8.4.4; version=8.4.4
Helmholz GmbH & Co. KG · REX 100version=0.0.0 <=3.0.2; version=3.0.2
MB connect line · mbNET.miniversion=0.0.0 <=3.0.2; version=3.0.2

Published CVSS scores

8.4CERT@VDECVSS:3.1/AV:L/AC:L/PR:N/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.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1287Improper Validation of Specified Type of Input
T1200Hardware Additions

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo