CVE-2021-34586

mediumpriority · track · 35EPSS 0.137 · 97 %ileDEEUUS

grimoire priorityP1 · Urgent

Exploitable?

—

no known exploitation

Likely / severe?

13.7% (97th) EPSS

CVSS 5 · medium

Is it mine?

83 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · nvd · phoenix_contact_psirt

EPSS · scored 2026-10-23

In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests may cause a Null pointer dereference in the CODESYS web server and may result in a denial-of-service condition.

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 |
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

cvss

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

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5

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

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 3.6

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · ENISA EU

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · info@cert.vde.comexploitability 3.9 · impact 3.6

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · Phoenix Contact PSIRT DE

v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-476USprimaryCWE-476US

affected products (83)

Products and version ranges known to be affected.

CODESYS CODESYS V2all web servers → V1.1.9.22enisa_euvdEU
codesys codesys< 1.1.9.22nvdUScpe:2.3:a:codesys:codesys:*:*:*:*:*:*:*:*
wago 750-8202 firmware< fw20nvdUScpe:2.3:o:wago:750-8202_firmware:*:*:*:*:*:*:*:*
wago 750-8203 firmware< fw20nvdUScpe:2.3:o:wago:750-8203_firmware:*:*:*:*:*:*:*:*
wago 750-8204 firmware< fw20nvdUScpe:2.3:o:wago:750-8204_firmware:*:*:*:*:*:*:*:*
wago 750-8206 firmware< fw20nvdUScpe:2.3:o:wago:750-8206_firmware:*:*:*:*:*:*:*:*
wago 750-8207 firmware< fw20nvdUScpe:2.3:o:wago:750-8207_firmware:*:*:*:*:*:*:*:*
wago 750-8208 firmware< fw20nvdUScpe:2.3:o:wago:750-8208_firmware:*:*:*:*:*:*:*:*
wago 750-8210 firmware< fw20nvdUScpe:2.3:o:wago:750-8210_firmware:*:*:*:*:*:*:*:*
wago 750-8211 firmware< fw20nvdUScpe:2.3:o:wago:750-8211_firmware:*:*:*:*:*:*:*:*
wago 750-8212 firmware< fw20nvdUScpe:2.3:o:wago:750-8212_firmware:*:*:*:*:*:*:*:*
wago 750-8213 firmware< fw20nvdUScpe:2.3:o:wago:750-8213_firmware:*:*:*:*:*:*:*:*
wago 750-8214 firmware< fw20nvdUScpe:2.3:o:wago:750-8214_firmware:*:*:*:*:*:*:*:*
wago 750-8216 firmware< fw20nvdUScpe:2.3:o:wago:750-8216_firmware:*:*:*:*:*:*:*:*
wago 750-8217 firmware< fw20nvdUScpe:2.3:o:wago:750-8217_firmware:*:*:*:*:*:*:*:*
wago 750-823 firmware< fw10nvdUScpe:2.3:o:wago:750-823_firmware:*:*:*:*:*:*:*:*
wago 750-829 firmware< fw17nvdUScpe:2.3:o:wago:750-829_firmware:*:*:*:*:*:*:*:*
wago 750-831 firmware< fw17nvdUScpe:2.3:o:wago:750-831_firmware:*:*:*:*:*:*:*:*
wago 750-832 firmware< fw10nvdUScpe:2.3:o:wago:750-832_firmware:*:*:*:*:*:*:*:*
wago 750-852 firmware< fw17nvdUScpe:2.3:o:wago:750-852_firmware:*:*:*:*:*:*:*:*

showing 20 of 83

advisories (1)

Vendor and ecosystem advisories describing this.

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

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd nvd phoenix_contact_psirt NVD CVE.org MITRE

published 2021-10-26modified 2026-06-17

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+8748 more

references (7)

External citations — patches, advisories, analysis.

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