CVE-2021-34595

mediumpriority · track · 32EPSS 0.009 · 58 %ileDEEUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
0.85% (58th) EPSS
CVSS 5.5 · medium
Is it mine?
99 products
Check your exposure
Who says so?
8 sources
cnnvd · enisa_euvd · cisa_csaf_ot · festo_psirt

EPSS · scored 2026-10-22

A crafted request with invalid offsets may cause an out-of-bounds read or write access in CODESYS V2 Runtime Toolkit 32 Bit full and PLCWinNT prior to versions V2.4.7.56, resulting in a denial-of-service condition or local memory overwrite.

01

remediations

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

A vendor fix is available.

  • Fixedphoenix_contact_psirt

    UPDATE A: fixed Firmware versions for 750-890/0xx-xxx, 750-891 and 750-893 We recommend all effected users with CODESYS 2.3 Runtime PLCs to update to the firmware version listed below. Series Ethernet Controller | Article Number | Fixed Firmware Versions | Available | |-------------------------|--------------------------|---------------------------| | 750-823 | >=FW10 | January 2022 | | 750-829 | >=FW17 | After BACnet certification | | 750-831/000-00x | >=FW17 | After BACnet certification | | 750-832/000-00x | >=FW10 | After BACnet certification | | 750-852 | >=FW17 | Q1 2022 | | 750-862 | >=FW10 | January 2022 | | 750-880/0xx-xxx | >=FW17 | Q1 2022 | | 750-881 | >=FW17 | Q1 2022 | | 750-882 | >=FW17 | Q1 2022 | | 750-885/0xx-xxx | >=FW17 | Q1 2022 | | 750-889 | >=FW17 | Q1 2022 | | 750-890/0xx-xxx | >=FW10 | January 2022 | | 750-891 | >=FW10 | January 2022 | | 750-893 | >=FW10 | January 2022 | PFC200 Controller | Article Number | Affected Firmware Versions | Approx. Available | |-------------------------|----------------------------|--------------------| | 750-8202/xxx-xxx | >=FW20 | January 2022 | | 750-8203/xxx-xxx | >=FW20 | January 2022 | | 750-8204/xxx-xxx | >=FW20 | January 2022 | | 750-8206/xxx-xxx | >=FW20 | January 2022 | | 750-8207/xxx-xxx | >=FW20 | January 2022 | | 750-8208/xxx-xxx | >=FW20 | January 2022 | | 750-8210/xxx-xxx | >=FW20 | January 2022 | | 750-8211/xxx-xxx | >=FW20 | January 2022 | | 750-8212/xxx-xxx | >=FW20 | January 2022 | | 750-8213/xxx-xxx | >=FW20 | January 2022 | | 750-8214/xxx-xxx | >=FW20 | January 2022 | | 750-8216/xxx-xxx | >=FW20 | January 2022 | | 750-8217/xxx-xxx | >=FW20 | January 2022 |

  • MitigationFesto Automation Suite <2.8.0.138 installed with CODESYS Development System 3.0festo_psirt

    Starting from Festo Automation Suite version 2.8.0.138, Codesys is no longer bundled with the suite and must be downloaded and installed separately by the customer. To mitigate this vulnerability customers are advised to: Download the latest, patched version of Codesys directly from the official Codesys website. Follow the installation and update instructions provided by Codesys to ensure all security fixes are applied. Regularly monitor Codesys security advisories and apply updates promptly. Maintain the Festo Automation Suite connector up to date by installing FAS updates as released by Festo.

  • MitigationFesto Automation Suite <2.8.0.138 installed with CODESYS Development System 3.5.16.10festo_psirt

    Starting from Festo Automation Suite version 2.8.0.138, Codesys is no longer bundled with the suite and must be downloaded and installed separately by the customer. To mitigate this vulnerability customers are advised to: Download the latest, patched version of Codesys directly from the official Codesys website. Follow the installation and update instructions provided by Codesys to ensure all security fixes are applied. Regularly monitor Codesys security advisories and apply updates promptly. Maintain the Festo Automation Suite connector up to date by installing FAS updates as released by Festo.

  • Mitigationphoenix_contact_psirt

    1. Use general security best practices to protect systems from local and network attacks. 2. Do not allow direct access to the device from untrusted networks. 3. Update to the latest firmware according to the table in chapter solutions. 4. Disable the CODESYS 2.3 WebVisualisation and CODESYS 2.3 port 2455. For further impact information and risk mitigation, please refer to the official CODESYS Advisory Website at https://www.codesys.com/security/security-reports.html

  • MitigationFesto Automation Suite <2.8.0.138 installed with CODESYS Development System 3.0cisa_csaf_ot

    Starting from Festo Automation Suite version 2.8.0.138, Codesys is no longer bundled with the suite and must be downloaded and installed separately by the customer. To mitigate this vulnerability customers are advised to: Download the latest, patched version of Codesys directly from the official Codesys website. Follow the installation and update instructions provided by Codesys to ensure all security fixes are applied. Regularly monitor Codesys security advisories and apply updates promptly. Maintain the Festo Automation Suite connector up to date by installing FAS updates as released by Festo.

  • MitigationFesto Automation Suite <2.8.0.138 installed with CODESYS Development System 3.5.16.10cisa_csaf_ot

    Starting from Festo Automation Suite version 2.8.0.138, Codesys is no longer bundled with the suite and must be downloaded and installed separately by the customer. To mitigate this vulnerability customers are advised to: Download the latest, patched version of Codesys directly from the official Codesys website. Follow the installation and update instructions provided by Codesys to ensure all security fixes are applied. Regularly monitor Codesys security advisories and apply updates promptly. Maintain the Festo Automation Suite connector up to date by installing FAS updates as released by Festo.

  • No fix availablepilz_psirt

    PMI 6 primo, PMCprimo C: No product-specific countermeasures available, please follow the general countermeasures. • PMCprimo C2, PMCprimo MC: Installation of Firmware Version 03.08.00 This update does not resolve the vulnerabilities (CVE-2021-34595, CVE-2021-34596, CVE-2021-34593, CVE-2021-30186, CVE-2021-30188, CVE-2021-30195, CVE-2019-19789) in the CODESYS V2 runtime system. The V2 runtime system is still included for compatibility reasons but is no longer supported by Pilz. Please migrate your application to the V3 runtime system or follow the general countermeasures.

  • No fix availablePMC programming tool 2.x.xpilz_psirt

    No product-specific countermeasures available, please follow the general countermeasures or migrate your application to the CODESYS V3 runtime system.

02

cvss

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

8.1
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5.5–8.1

v2.05.5mediumAV:N/AC:L/Au:S/C:N/I:P/A:Pprimary · NVD / NIST USexploitability 8 · impact 4.9
v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hprimary · NVD / NIST USexploitability 2.8 · impact 5.2
v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hsecondary · CISA US
v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hsecondary · ENISA EU
v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hsecondary · info@cert.vde.comexploitability 2.8 · impact 5.2
v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hsecondary · Phoenix Contact PSIRT DE
v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hsecondary · Pilz PSIRT DE
v3.18.1highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:Hsecondary · Festo PSIRT DE
v3.17.4highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-119USprimaryCWE-119USCWE-823USCWE-823USCWE-823USCWE-823US
04

affected products (99)

Products and version ranges known to be affected.

showing 20 of 99
05

advisories (6)

Vendor and ecosystem advisories describing this.

  • FSA-202601Several CODESYS vulnerabilities in Festo Automation Suite2026-02-26csaf · festo_psirtDE

    Starting with Festo Automation Suite (FAS) version 2.8.0.138, the suite is delivered only with a connector to Codesys, rather than including Codesys directly. Prior to this version, Codesys was bundled within the FAS installation. From version 2.8.0.138 onwards, customers are required to download and install Codesys independently. This change impacts the handling of security vulnerabilities (CVEs) related to Codesys. Any Codesys-related security issues must now be addressed by the customer through their separate Codesys installation. The FAS itself includes only the connector component, which is maintained and updated within the suite. Please ensure that Codesys is kept up to date independently to mitigate any potential security risks associated with the Codesys software.

  • VDE-2021-054Pilz: Multiple vulnerabilities in CODESYS V2 and V3 runtime system2022-04-26csaf · pilz_psirtDE

    Several Pilz products use Versions V2 and V3 of the CODESYS runtime system from CODESYS GmbH, which enables the execution of IEC 61131-3 PLC programs. These runtime environments contain several vulnerabilities, which an attacker can exploit via the network. Successful exploitation of the vulnerabilities results in reduced availability and, in a worst case, to the insertion of program code.

  • VDE-2021-055Pilz: PMC programming tool 2.x.x affected by multiple vulnerabilities2022-04-26csaf · pilz_psirtDE

    The software product PMC programming tool from Pilz is based on the software CODESYS Development System from CODESYS GmbH. This software is affected by several vulnerabilities, which an attacker can exploit locally or via the network. This means that, in a worst case, attackers could execute arbitrary program code on the PC on which the PMC programming tool is used.

  • VDE-2021-056WAGO: Multiple Vulnerabilities in CODESYS Runtime 2.3 and WebVisualisation2021-11-16csaf · phoenix_contact_psirtDE

    Multiple vulnerabilities were reported in CODESYS 2.3 Runtime. The CODESYS 2.3 Runtime is an essential component in several WAGO PLCs. All vulnerable PLCs are listed in chapter 'Affected Products'. https://www.codesys.com/security/security-reports.html

  • WID-SEC-W-2023-0825ABB AC-500: Mehrere SchwachstellenDeutsch2023-04-02csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in ABB AC-500 ausnutzen, um beliebigen Programmcode auszuführen, Informationen offenzulegen, einen Denial of Service Zustand herbeizuführen oder Dateien zu manipulieren.

  • ICSA-26-076-01CODESYS in Festo Automation Suite2026-02-26icsa · cisa_csaf_otUS

    Starting with Festo Automation Suite (FAS) version 2.8.0.138, the suite is delivered only with a connector to Codesys, rather than including Codesys directly. Prior to this version, Codesys was bundled within the FAS installation. From version 2.8.0.138 onwards, customers are required to download and install Codesys independently. This change impacts the handling of security vulnerabilities (CVEs) related to Codesys. Any Codesys-related security issues must now be addressed by the customer through their separate Codesys installation. The FAS itself includes only the connector component, which is maintained and updated within the suite. Please ensure that Codesys is kept up to date independently to mitigate any potential security risks associated with the Codesys software.

06

also known as (3)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

cnnvdenisa_euvdcisa_csaf_otfesto_psirtnvdpilz_psirtphoenix_contact_psirtcert_bundNVDCVE.orgMITRE
published 2021-10-26modified 2026-06-17
09

references (4)

External citations — patches, advisories, analysis.

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