CVE-2026-35227

mediumpriority · track · 0EPSS 0.004 · 29 %ileDEEU
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
0.35% (29th) EPSS
CVSS 5.9 · medium
Is it mine?
5 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · cert_bund · codesys_psirt

EPSS · scored 2026-10-27

An unauthenticated remote attacker may exhaust all available TCP connections in the CODESYS Modbus TCP Server stack if a race condition in connection handling is successfully exploited, preventing legitimate clients from establishing new connections.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

  • FixedCODESYS Modbuscodesys_psirt

    Update the following product to version 4.6.0.0. * CODESYS Modbus To make the fix effective for existing CODESYS projects, you must additionally update the local Modbus TCP Server in the device tree to the latest version and perform a download of the CODESYS application to the PLC. The CODESYS Development System and the products available as CODESYS add-ons can be downloaded and installed directly with the CODESYS Installer or be downloaded from the CODESYS Store. Alternatively, as well as for all other products, you will find further information on obtaining the software update in the CODESYS Update area https://www.codesys.com/download/.

02

cvss

Technical severity, 0–10. One row per scoring source.

8.2
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.6–8.2

v3.15.9mediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · CODESYS PSIRT
v4.08.2highCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:Nsecondary · ENISA EU
v4.08.2highCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Xsecondary · info@cert.vde.com
v4.04.6mediumCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Xsecondary · CVSS-BT (t0sche)
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-772USCWE-772US
05

affected products (5)

Products and version ranges known to be affected.

06

advisories (2)

Vendor and ecosystem advisories describing this.

  • Advisory2026-05_VDE-2026-042CODESYS Modbus TCP Server - Improper resource management2026-05-12csaf · codesys_psirtDE

    CODESYS Modbus is an add‑on for the CODESYS Development System that provides a fully integrated Modbus protocol stack along with diagnostic capabilities. A flaw in the CODESYS Modbus TCP Server protocol stack library results in a vulnerability. When a Modbus TCP server is configured, this vulnerable protocol stack is downloaded to and executed by CODESYS Control runtime systems. The vulnerability is caused by a resource management issue in the Modbus TCP server and is only exploitable if a race condition in the connection handling is successfully triggered. Over time, this may exhaust the configured maximum number of connections, potentially preventing new connections from being accepted. Existing connections remain unaffected and continue to operate normally. This issue affects only CODESYS projects that include a Modbus TCP server configuration.

  • WID-SEC-W-2026-1464CODESYS Modbus: Schwachstelle ermöglicht Denial of ServiceDeutsch2026-05-11csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann eine Schwachstelle in CODESYS Modbus ausnutzen, um einen Denial of Service Angriff durchzuführen.

07

also known as (3)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

cnnvdenisa_euvdcert_bundcodesys_psirtNVDCVE.orgMITRE
published 2026-05-12modified 2026-10-26
09

references (5)

External citations — patches, advisories, analysis.

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