CVE-2021-34594

Beckhoff TwinCAT OPC UA Server in TF6100 < 4.3.48.0 — vulnerability CVE-2021-34594

TwinCAT OPC UA Server in TF6100 and TS6100 in product versions before 4.3.48.0 or with TcOpcUaServer versions below 3.2.0.194 are prone to a relative path traversal that allow administrators to create or delete any files on the system.

CVSS 6.5No patch available

This record: live connection— last retrieved: 7 November 2026 at 14:22.

Vendor

Beckhoff

Products

TwinCAT OPC UA Server in TF6100 < 4.3.48.0, TwinCAT OPC UA Server in TS6100 < 4.3.48.0

up to version <3.2.0.194

Published

4 November 2021

Last modified

17 June 2026

Original source information

Taken directly from NVD, CISA or the vendor — sometimes in English, unchanged from the source.

Technical description

CVSS 3.1 — vector details

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H

Attack vector

NETWORK

Privileges required

HIGH

User interaction

NONE

Confidentiality

None

Integrity

High

Availability

High

EPSS — Exploit Prediction Scoring System

Probability of exploitation within 30 days

1.1%

Percentile

66e

Source: FIRST.org, updated on 6 November 2026.

Patch information

Consider restricting access to the nodes of the 'TcOpcUAServer' with the methods described by https://infosys.beckhoff.com/content/1033/tcopcuaserver/5930038411-1.html such that the administrative interface can only be accessed by administrative users of well known OPC UA clients.

IACS Radar assessment

Our own interpretation and context for the source data above.

IACS Radar assessment

Our own interpretation and context for this vulnerability — not an official source.

IACS Radar priority score

51/ 100

Based on CVSS 6.5, EPSS 1.1%, industrial relevance 80/100.

Combines CVSS, EPSS, KEV status, industrial relevance and exposure relevance — a complement to, not a replacement for, the individual scores below and above.

Conditions for exploitation

•Network access to the affected device or segment is required.
•Limited user privileges are required.
•No user interaction required.

Operational impact & energy relevance

Possible loss of visibility of or control over the process upon successful exploitation.

Assessed as relevant to the energy sector based on: Vermeld in een officiële CISA ICS Advisory, wat directe relevantie voor industriële besturingssystemen bevestigt. Productbeschrijving komt overeen met de categorie "opc-server", een typisch OT/ICS-componenttype. Vendor "Beckhoff" is a known supplier of equipment for the energy sector. Description mentions industrial protocol: opc-ua.

Recommended defensive measures

•Apply the latest firmware or software update and validate its integrity.
•Encrypt sensitive configuration and management communication.
•Restrict network access to the affected device to a dedicated OT management segment.
•Implement network segmentation in line with zones and conduits (IEC 62443-3-2).

Industrial relevance score

80/ 100

• Mentioned in an official CISA ICS advisory, which confirms direct relevance to industrial control systems.
• Product description matches the category "opc-server", a typical OT/ICS component type.
• Vendor "Beckhoff" is a known supplier of equipment for the energy sector.
• Description mentions industrial protocol: opc-ua.

Automatically classified as industrially relevant based on CISA/NVD signals (see reasons).

Classified by IACS Radar-analysepijplijn (geautomatiseerd) on 7 November 2026.

IEC 62443 mapping

IEC 62443-4-1IEC 62443-4-2FR3 · SysteemintegriteitFR4 · Vertrouwelijkheid van gegevens

Automatic IACS Radar assessment based on the reported CWE weakness classification; not an official certification statement.

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