CVE-2021-34570

highpriority · track · 30EPSS 0.010 · 62 %ileDEEUUS

grimoire priorityP2 · Scheduled

Exploitable?

—

no known exploitation

Likely / severe?

0.98% (62nd) EPSS

CVSS 7.8 · high

Is it mine?

24 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · nvd · phoenix_contact_psirt

EPSS · scored 2026-10-27

Multiple Phoenix Contact PLCnext control devices in versions prior to 2021.0.5 LTS are prone to a DoS attack through special crafted JSON requests.

remediations

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

A vendor fix is available.

Fixedphoenix_contact_psirt
Phoenix Contact recommends affected users to upgrade to the current Firmware 2021.0.5 LTS or higher which fixes this vulnerability. | Article no | Article | |------------|--------------------------------| | 1151412 | AXC F 1152 | | 2404267 | AXC F 2152 | | 1069208 | AXC F 3152 | | 1051328 | RFC 4072S | | 1046568 | AXC F 2152 Starterkit | | 1188165 | PLCnext Technology Starterkit |
Mitigationphoenix_contact_psirt
Phoenix Contact recommends operating network-capable devices in closed networks or protected with a suitable firewall. For detailed information on our recommendations for measures to protect network-capable devices, please refer to our application note: Measures to protect network-capable devices with Ethernet connection

cvss

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

7.8

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.9–7.8

v2.07.8highAV:N/AC:L/Au:N/C:N/I:N/A:Cprimary · NVD / NIST USexploitability 10 · impact 6.9

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-20USCWE-20US

affected products (24)

Products and version ranges known to be affected.

PHOENIX CONTACT AXC FAXC F 1152 (1151412) → 2021.0.5 LTSenisa_euvdEU
PHOENIX CONTACT AXC FAXC F 2152 (2404267) → 2021.0.5 LTSenisa_euvdEU
PHOENIX CONTACT AXC FAXC F 2152 Starterkit (1046568) → 2021.0.5 LTSenisa_euvdEU
PHOENIX CONTACT AXC FAXC F 3152 (1069208) → 2021.0.5 LTSenisa_euvdEU
PHOENIX CONTACT PLCnextPLCnext Technology Starterkit (1188165) → 2021.0.5 LTSenisa_euvdEU
PHOENIX CONTACT RFCRFC 4072S (1051328) → 2021.0.5 LTSenisa_euvdEU
phoenixcontact axc f 1152 firmware< 2021.0.5nvdUScpe:2.3:o:phoenixcontact:axc_f_1152_firmware:*:*:*:*:*:*:*:*
phoenixcontact axc f 2152 firmware< 2021.0.5nvdUScpe:2.3:o:phoenixcontact:axc_f_2152_firmware:*:*:*:*:*:*:*:*
phoenixcontact axc f 2152 starterkit firmware< 2021.0.5nvdUScpe:2.3:o:phoenixcontact:axc_f_2152_starterkit_firmware:*:*:*:*:*:*:*:*
phoenixcontact axc f 3152 firmware< 2021.0.5nvdUScpe:2.3:o:phoenixcontact:axc_f_3152_firmware:*:*:*:*:*:*:*:*
phoenixcontact plcnext technology starterkit firmware< 2021.0.5nvdUScpe:2.3:o:phoenixcontact:plcnext_technology_starterkit_firmware:*:*:*:*:*:*:*:*
phoenixcontact rfc 4072s firmware< 2021.0.5nvdUScpe:2.3:o:phoenixcontact:rfc_4072s_firmware:*:*:*:*:*:*:*:*
Firmware 2021.0.5 LTS installed on AXC F 1152all versionsfixedphoenix_contact_psirtDE
Firmware 2021.0.5 LTS installed on AXC F 2152all versionsfixedphoenix_contact_psirtDE
Firmware 2021.0.5 LTS installed on AXC F 2152 Starterkitall versionsfixedphoenix_contact_psirtDE
Firmware 2021.0.5 LTS installed on AXC F 3152all versionsfixedphoenix_contact_psirtDE
Firmware 2021.0.5 LTS installed on PLCnext Technology Starterkitall versionsfixedphoenix_contact_psirtDE
Firmware 2021.0.5 LTS installed on RFC 4072Sall versionsfixedphoenix_contact_psirtDE
Firmware <2021.0.5 LTS installed on AXC F 1152all versionsphoenix_contact_psirtDE
Firmware <2021.0.5 LTS installed on AXC F 2152all versionsphoenix_contact_psirtDE

showing 20 of 24

advisories (1)

Vendor and ecosystem advisories describing this.

VDE-2021-029PHOENIX CONTACT: DoS for PLCnext Control devices in versions <2021.0.5 LTS2021-08-04csaf · phoenix_contact_psirtDE
A device on the same network as the controller sending a special crafted JSON request to the /auth/access-token endpoint may cause the controller to restart (CWE-20). UPDATE A The CVSS score has been raised from 7.7 (CVSS:3.0:AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H) to 9.1 (CVSS:3.0:AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H)

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 2021-09-27modified 2026-06-17

references (3)

External citations — patches, advisories, analysis.

scry

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