Skip to content
Fencer Vulns
medium 5.3

CVE-2021-20598 json

Overly Restrictive Account Lockout Mechanism vulnerability in Mitsubishi Electric MELSEC iQ-R series CPU modules (R08/16/32/120SFCPU all ve…

published 2021-08-06 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-8016

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

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.

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-21-250-01 updated cvss 3.7

Mitsubishi Electric MELSEC iQ-R Series

  • Mitsubishi Electric Corporation MELSEC iQ-R series Safety CPU R08SFCPU Mitsubishi Electric Corporation MELSEC iQ-R series Safety CPU R16SFCPU Mitsubishi Electric Corporation MELSEC iQ-R series Safety CPU R32SFCPU Mitsubishi Electric Corporation MELSEC iQ-R series Safety CPU R120SFCPU Mitsubishi Electric Corporation MELSEC iQ-R series SIL2 Process CPU R08PSFCPU Mitsubishi Electric Corporation MELSEC iQ-R series SIL2 Process CPU R16PSFCPU
    +2 more products
    Mitsubishi Electric Corporation MELSEC iQ-R series SIL2 Process CPU R32PSFCPU Mitsubishi Electric Corporation MELSEC iQ-R series SIL2 Process CPU R120PSFCPU
    affected: mitigation “MELSEC iQ-R series Safety CPU R08/16/32/120SFCPU:Firmware versions "27" or later” mitsubishifa.co.th

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

Exploit prediction

1.51% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • n/a MELSEC iQ-R series CPU modules R08/16/32/120SFCPU; R08/16/32/120PSFCPU

Classification

Weakness

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.