How severe is CVE-2021-20598?

CVE-2021-20598 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2021-20598 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-20598?

CVE-2021-20598 primarily affects Mitsubishielectric R08sfcpu Firmware. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-20598?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-20598 published?

CVE-2021-20598 was published on 2021-08-06 and last updated on 2026-06-17.

CVE-2021-20598

CVE-2021-20598 is a medium-severity vulnerability in Mitsubishielectric R08sfcpu Firmware with a CVSS 3.x base score of 5.3. 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-287.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 2% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Mitsubishielectric R08sfcpu Firmware
Published: 2021-08-06
Last modified: 2026-06-17

Description

Overly Restrictive Account Lockout Mechanism vulnerability in Mitsubishi Electric MELSEC iQ-R series CPU modules (R08/16/32/120SFCPU all versions, R08/16/32/120PSFCPU all versions) allows a remote unauthenticated attacker to lockout a legitimate user by continuously trying login with incorrect password.

Frequently asked questions

What is CVE-2021-20598?: Overly Restrictive Account Lockout Mechanism vulnerability in Mitsubishi Electric MELSEC iQ-R series CPU modules (R08/16/32/120SFCPU all versions, R08/16/32/120PSFCPU all versions) allows a remote unauthenticated attacker to lockout a legitimate user by continuously trying login with incorrect password.
How severe is CVE-2021-20598?: CVE-2021-20598 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2021-20598 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-20598?: CVE-2021-20598 primarily affects Mitsubishielectric R08sfcpu Firmware. In total, 8 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-20598?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-20598 published?: CVE-2021-20598 was published on 2021-08-06 and last updated on 2026-06-17.

References

Affected products (8)

cpe:2.3:o:mitsubishielectric:r08sfcpu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:r16sfcpu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:r32sfcpu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:r120sfcpu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:r08psfcpu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:r16psfcpu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:r32psfcpu_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:mitsubishielectric:r120psfcpu_firmware:*:*:*:*:*:*:*:*

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Other CWE-287 (Improper Authentication) vulnerabilities

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CVE-2026-47280 — Critical (CVSS 10.0): Improper authentication in Azure Resource Manager (ARM) allows an unauthorized attacker to elevate privileges over a…
CVE-2026-42822 — Critical (CVSS 10.0): Improper authentication in Azure Local Disconnected Operations allows an unauthorized attacker to elevate privileges…
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