CODESYS Modbus prior 4.6.0.0 TCP Connection release of resource

CVSS Meta Temp Score
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CTI Interest Score
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7.2$0-$5k0.00

Summaryinfo

A vulnerability was found in CODESYS Modbus. It has been declared as critical. This affects an unknown function of the component TCP Connection Handler. Such manipulation leads to release of resource. This vulnerability is uniquely identified as CVE-2026-35227. The attack can be launched remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in CODESYS Modbus. It has been rated as critical. Affected by this issue is some unknown processing of the component TCP Connection Handler. The manipulation with an unknown input leads to a release of resource vulnerability. Using CWE to declare the problem leads to CWE-772. The product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed. Impacted is availability. CVE summarizes:

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.

The advisory is available at certvde.com. This vulnerability is handled as CVE-2026-35227 since 04/01/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 4.6.0.0 eliminates this vulnerability.

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Productinfo

Vendor

Name

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 7.5
VulDB Meta Temp Score: 7.2

VulDB Base Score: 7.5
VulDB Temp Score: 7.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Release of resource
CWE: CWE-772 / CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Modbus 4.6.0.0

Timelineinfo

04/01/2026 CVE reserved
05/12/2026 +41 days Advisory disclosed
05/12/2026 +0 days VulDB entry created
05/12/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: VDE-2026-042
Status: Confirmed

CVE: CVE-2026-35227 (🔒)
GCVE (CVE): GCVE-0-2026-35227
GCVE (VulDB): GCVE-100-362942

Entryinfo

Created: 05/12/2026 11:00
Changes: 05/12/2026 11:00 (66)
Complete: 🔍
Cache ID: 216::103

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