How severe is CVE-2020-5594?

CVE-2020-5594 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-5594 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-5594?

CVE-2020-5594 primarily affects Mitsubishielectric Melsec Iq-r Firmware. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-5594?

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

When was CVE-2020-5594 published?

CVE-2020-5594 was published on 2020-06-23 and last updated on 2026-06-17.

CVE-2020-5594

CVE-2020-5594 is a critical-severity vulnerability in Mitsubishielectric Melsec Iq-r Firmware with a CVSS 3.x base score of 9.8. 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-319.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-319
Affected product: Mitsubishielectric Melsec Iq-r Firmware
Published: 2020-06-23
Last modified: 2026-06-17

Description

Mitsubishi Electric MELSEC iQ-R, iQ-F, Q, L, and FX series CPU modules all versions contain a vulnerability that allows cleartext transmission of sensitive information between CPU modules and GX Works3 and/or GX Works2 via unspecified vectors.

Frequently asked questions

What is CVE-2020-5594?: Mitsubishi Electric MELSEC iQ-R, iQ-F, Q, L, and FX series CPU modules all versions contain a vulnerability that allows cleartext transmission of sensitive information between CPU modules and GX Works3 and/or GX Works2 via unspecified vectors.
How severe is CVE-2020-5594?: CVE-2020-5594 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-5594 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-5594?: CVE-2020-5594 primarily affects Mitsubishielectric Melsec Iq-r Firmware. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-5594?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-5594 published?: CVE-2020-5594 was published on 2020-06-23 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:o:mitsubishielectric:melsec_iq-r_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:melsec_iq-f_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:melsec-q_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:melsec-l_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:melsec-fx_firmware:*:*:*:*:*:*:*:*

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