CVE-2021-20598

mediumpriority · track · 22EPSS 0.015 · 74 %ileEURUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
1.51% (74th) EPSS
CVSS 5 · medium
Is it mine?
33 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · fstec_bdu · cisa_csaf_ot

EPSS · scored 2026-10-26

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.

01

remediations

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

No vendor fix yet; a mitigation is available.

  • MitigationMELSEC iQ-R Series SIL2 Process CPU R08PSFCPUcisa_csaf_ot

    MELSEC iQ-R series SIL2 Process CPU R08/16/32/120PSFCPU:Firmware versions "12" or later

  • MitigationMELSEC iQ-R Series SIL2 Process CPU R120PSFCPUcisa_csaf_ot

    MELSEC iQ-R series SIL2 Process CPU R08/16/32/120PSFCPU:Firmware versions "12" or later

  • MitigationMELSEC iQ-R Series SIL2 Process CPU R16PSFCPUcisa_csaf_ot

    MELSEC iQ-R series SIL2 Process CPU R08/16/32/120PSFCPU:Firmware versions "12" or later

  • MitigationMELSEC iQ-R Series SIL2 Process CPU R32PSFCPUcisa_csaf_ot

    MELSEC iQ-R series SIL2 Process CPU R08/16/32/120PSFCPU:Firmware versions "12" or later

  • MitigationMELSEC iQ-R Series Safety CPU R08SFCPUcisa_csaf_ot

    MELSEC iQ-R series SIL2 Process CPU R08/16/32/120PSFCPU:Firmware versions "12" or later

  • MitigationMELSEC iQ-R Series Safety CPU R120SFCPUcisa_csaf_ot

    MELSEC iQ-R series SIL2 Process CPU R08/16/32/120PSFCPU:Firmware versions "12" or later

  • MitigationMELSEC iQ-R Series Safety CPU R16SFCPUcisa_csaf_ot

    MELSEC iQ-R series SIL2 Process CPU R08/16/32/120PSFCPU:Firmware versions "12" or later

  • MitigationMELSEC iQ-R Series Safety CPU R32SFCPUcisa_csaf_ot

    MELSEC iQ-R series SIL2 Process CPU R08/16/32/120PSFCPU:Firmware versions "12" or later

02

cvss

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

5.3
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 3.7–5.3

v2.05mediumAV:N/AC:L/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 10 · impact 2.9
v3.15.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lprimary · NVD / NIST USexploitability 3.9 · impact 1.4
v3.13.7lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · CISA US
v3.15.3mediumAV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · FSTEC (BDU) RU
v3.14.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:Usecondary · CVSS-BT (t0sche)
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-287USprimaryCWE-287USCWE-645USCWE-645US
04

affected products (33)

Products and version ranges known to be affected.

showing 20 of 33
05

advisories (1)

Vendor and ecosystem advisories describing this.

  • ICSA-21-250-01Mitsubishi Electric MELSEC iQ-R Series2021-09-07icsa · cisa_csaf_otUS

    Successful exploitation of these vulnerabilities could allow a remote attacker unauthorized access to legitimate usernames, CPU module access, or the ability to deny access to legitimate users.

06

also known as (5)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducisa_csaf_otNVDCVE.orgMITRE
published 2021-08-06modified 2026-06-17
09

references (9)

External citations — patches, advisories, analysis.

scry

Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.

Free scan