How severe is CVE-2020-7566?

CVE-2020-7566 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2020-7566 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-7566?

CVE-2020-7566 affects Schneider-electric Modicon M221 Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-7566?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-7566 published?

CVE-2020-7566 was published on 2020-11-19 and last updated on 2026-06-17.

CVE-2020-7566

CVE-2020-7566 is a high-severity vulnerability in Schneider-electric Modicon M221 Firmware with a CVSS 3.x base score of 7.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-334.

Key facts

Severity: High (CVSS 3.x base score 7.3)
CVSS v2: 4.3
EPSS exploit prediction: 0% (21st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-334
Affected product: Schneider-electric Modicon M221 Firmware
Published: 2020-11-19
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2020-7566?: 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.
How severe is CVE-2020-7566?: CVE-2020-7566 has a CVSS 3.x base score of 7.3, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2020-7566 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-7566?: CVE-2020-7566 affects Schneider-electric Modicon M221 Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-7566?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-7566 published?: CVE-2020-7566 was published on 2020-11-19 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:schneider-electric:modicon_m221_firmware:-:*:*:*:*:*:*:*

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