CVE-2020-12526

mediumpriority · track · 21EPSS 0.010 · 61 %ileDEEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.95% (61st) EPSS

CVSS 5 · medium

Is it mine?

13 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · fstec_bdu · beckhoff_psirt

EPSS · scored 2026-10-27

TwinCAT OPC UA Server in versions up to 2.3.0.12 and IPC Diagnostics UA Server in versions up to 3.1.0.1 from Beckhoff Automation GmbH & Co. KG are vulnerable to denial of service attacks. The attacker needs to send several specifically crafted requests to the running OPC UA server. After some of these requests the OPC UA server is no longer responsive to any client. This is without effect to the real-time functionality of IPCs.

remediations

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

A vendor fix is available.

Fixedbeckhoff_psirt
For devices running Windows but not Windows CE or TwinCAT/BSD please get a recent version of the OPC UA servers through the conventional ways and update your system. For devices running Windows CE please request a recent image via Beckhoff's support and apply it to your device. For the product CX8091 please use firmware version "CX8091_CE600_LF_v356f_TC211R3_B2306_v2" or later which can be downloaded at https://download.beckhoff.com/download/software/embPC-Control/CX80x0/CX8091/OPC-update Please note that the updated OPC UA server leaves less RAM available to your application on the CX8091.
Mitigationbeckhoff_psirt
Consider disabling the IPC Diagnostics Server by stopping and disabling the corresponding Windows service or service. For example this can be achieved with the following PowerShell commands: Stop-Service -Force -Name DevMgrSvr-UA Set-Service -Name DevMgrSvr-UA -StartupType Disabled Alternatively consider limiting access to the TCP port the OPC UA server is listening on. This can happen with a dedicated firewall appliance which sits in front of an affected device. Alternatively at the device the Windows firewall can be configured to limit access to the TCP port. Further guidance is provided within the "Security Guide IPC" from Beckhoff which is accessible at https://www.beckhoff.com/secguide

cvss

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

5.3

010

base score 0–10 · higher = more severe · hover a vector to decode

v2.05mediumAV:N/AC:L/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 10 · impact 2.9

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lprimary · NVD / NIST USexploitability 3.9 · impact 1.4

v3.15.3mediumAV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · FSTEC (BDU) RU

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · ENISA EU

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · info@cert.vde.comexploitability 3.9 · impact 1.4

v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · Beckhoff PSIRT DE

v3.14.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-20USprimaryCWE-20USCWE-20US

affected products (13)

Products and version ranges known to be affected.

Vendor IPC Diagnostics UA Server≤ 3.1.0.1beckhoff_psirtDE
Vendor IPC Diagnostics UA Server <=3.1.0.1≤ 3.1.0.1beckhoff_psirtDE
Vendor TwinCAT OPC UA Server≤ 2.3.0.12beckhoff_psirtDE
Vendor TwinCAT OPC UA Server <=2.3.0.12≤ 2.3.0.12beckhoff_psirtDE
Beckhoff IPC Diagnostics UA Server≤ unspecified ≤3.1.0.1enisa_euvdEU
Beckhoff TF6100≤ unspecified ≤3.3.18enisa_euvdEU
Beckhoff TwinCAT OPC UA Server≤ unspecified ≤2.3.0.12enisa_euvdEU
Beckhoff Automation GmbH & Co. KG IPC Diagnostics UA Server≤ 3.1.0.1fstec_bduRU
Beckhoff Automation GmbH & Co. KG TF6100≤ 3.3.18fstec_bduRU
Beckhoff Automation GmbH & Co. KG TwinCAT OPC UA Server≤ 2.3.0.12fstec_bduRU
beckhoff ipc diagnostics ua server≤ 3.1.0.1nvdUScpe:2.3:a:beckhoff:ipc_diagnostics_ua_server:*:*:*:*:*:*:*:*
beckhoff tf6100≤ 3.3.18nvdUScpe:2.3:a:beckhoff:tf6100:*:*:*:*:*:*:*:*
beckhoff twincat opc ua server≤ 2.3.0.12nvdUScpe:2.3:a:beckhoff:twincat_opc_ua_server:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

VDE-2020-051Beckhoff: DoS-Vulnerability for TwinCAT OPC UA Server and IPC Diagnostics UA Server2021-04-27csaf · beckhoff_psirtDE
Some TwinCAT OPC UA Server and IPC Diagnostics UA Server versions from Beckhoff Automation GmbH & Co. KG are vulnerable to denial of service attacks. The attacker needs to send several specifically crafted requests to the running OPC UA server. After some of these requests the OPC UA server is no longer responsive to any client. This is without effect to the real-time functionality of IPCs. UPDATE A - 11.05.2021 Please note that some hardware products from Beckhoff are shipped with a TwinCAT OPC UA Server pre-installed. In some cases the server is enabled by default. IPC Diagnostics UA Server (contained in Beckhoff's Windows images) server versions up to and including 3.1.0.1 are affected Please note that IPC products from Beckhoff are shipped with an IPC Diagnostics UA Server pre-installed. In all cases the server is disabled by default. The version numbers named above always refer to the version number which is accessible via OPC UA at the server via the standard OPC UA node /Objects/Server/ServerStatus/BuildInfo/SoftwareVersion and on Windows also as the file property "File version" of the file TcOpcUaServer.exe for TwinCAT OPC UA Server respectively the file DevMgrSvr-UA.exe for IPC Diagnostics UA Server. UPDATE A - 11.05.2021 Please note that IPC products from Beckhoff are shipped with an IPC Diagnostics UA Server pre-installed. While on Windows CE it is disabled by default all other Windows images have it enabled by default.

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu beckhoff_psirt nvd NVD CVE.org MITRE

published 2021-05-13modified 2026-06-17

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references (6)

External citations — patches, advisories, analysis.

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