CVE-2020-7566

mediumpriority · track · 29EPSS 0.003 · 22 %ileEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.29% (22nd) EPSS

CVSS 4.3 · medium

Is it mine?

7 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · fstec_bdu · cisa_csaf_ot

EPSS · scored 2026-10-27

A CWE-334: Small Space of Random Values vulnerability exists in Modicon M221 (all references, all versions) that could allow the attacker to break the encryption keys when the attacker has captured the traffic between EcoStruxure Machine - Basic software and Modicon M221 controller.

remediations

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

A vendor fix is available.

FixedModicon M221cisa_csaf_ot
Within the Modicon M221 application, the user must: Disable all unused protocols, especially programming protocol, as described in section “Configuring Ethernet Network” of EcoStruxure Machine Expert - Basic online help for the M221 PLC. This action will prevent unintended remote programming access.;Set a password to protect the project.;Set a password for read access on the controller.;Set a different password for write access on the controller.
MitigationModicon M221cisa_csaf_ot
Install physical controls so no unauthorized personnel can access industrial control and safety systems, components, peripheral equipment, and networks.

cvss

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

7.3

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 4.3–7.3

v2.04.3mediumAV:A/AC:M/Au:N/C:P/I:P/A:Nprimary · NVD / NIST USexploitability 5.5 · impact 4.9

v3.17.3highCVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:Nprimary · NVD / NIST USexploitability 2.1 · impact 5.2

v3.07.1highCVSS:3.0/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · CISA US

v3.17.1highAV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU

v3.17.1highCVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondary · ENISA EU

v3.17.1highCVSS:3.1/AV:A/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:Hsecondaryexploitability 1.2 · impact 5.9

v3.16.7mediumCVSS:3.1/AV:A/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: no · Technical Impact: totalcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-334USCWE-334USCWE-334US

affected products (7)

Products and version ranges known to be affected.

Modicon M221: all versionsall versionscisa_csaf_otUS
Schneider Electric Software, LLC Modicon M221all versionscisa_csaf_otUS
n/a Modicon M221, all references, all versions≤ Modicon M221, all references, all versionsenisa_euvdEU
Schneider Electric Modicon M100all versionsfstec_bduRU
Schneider Electric Modicon M200all versionsfstec_bduRU
Schneider Electric Modicon M221all versionsfstec_bduRU
schneider-electric modicon m221 firmwareall versionsnvdUScpe:2.3:o:schneider-electric:modicon_m221_firmware:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

ICSA-20-343-04Schneider Electric Modicon M221 Programmable Logic Controller2020-12-08icsa · cisa_csaf_otUS
Successful exploitation of these vulnerabilities could allow an attacker to take control over the PLC and gain unauthorized access, which could result in exposure of sensitive information.

also known as (4)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cisa_csaf_ot nvd NVD CVE.org MITRE

published 2020-11-19modified 2026-06-17

references (7)

External citations — patches, advisories, analysis.

scry

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