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Fencer Intel
critical 9.1

CVE-2021-20599 json

Cleartext Transmission of Sensitive InformationCleartext transmission of sensitive information vulnerability in MELSEC iQ-R series Safety C…

published 5y ago modified 4mo ago also EUVD-2021-8017

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.4%
EPSS 1.4% chance of exploitation in 30 days, percentile 72%
public exploits
0
none known

Summary

Cleartext Transmission of Sensitive InformationCleartext transmission of sensitive information vulnerability in MELSEC iQ-R series Safety CPU R08/16/32/120SFCPU firmware versions "26" and prior and MELSEC iQ-R series SIL2 Process CPU R08/16/32/120PSFCPU firmware versions "11" and prior allows a remote unauthenticated attacker to login to a target CPU module by obtaining credentials other than password.

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Vendor advisories

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

cisa ICSA-21-287-03 updated cvss 9.1

Mitsubishi Electric MELSEC iQ-R Series

  • Mitsubishi Electric Corporation MELSEC iQ-R series Safety CPU R08SFCPU Firmware <=26 Mitsubishi Electric Corporation MELSEC iQ-R series Safety CPU R16SFCPU Firmware <=26 Mitsubishi Electric Corporation MELSEC iQ-R series Safety CPU R32SFCPU Firmware <=26 Mitsubishi Electric Corporation MELSEC iQ-R series Safety CPU R120SFCPU Firmware <=26 Mitsubishi Electric Corporation MELSEC iQ-R series SIL2 Process CPU R08PSFCPU Firmware <=11 Mitsubishi Electric Corporation MELSEC iQ-R series SIL2 Process CPU R16PSFCPU Firmware <=11
    +2 more products
    Mitsubishi Electric Corporation MELSEC iQ-R series SIL2 Process CPU R32PSFCPU Firmware <=11 Mitsubishi Electric Corporation MELSEC iQ-R series SIL2 Process CPU R120PSFCPU Firmware <=11
    affected: mitigation “Mitsubishi Electric has prepared the following countermeasures:” mitsubishielectric.com

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

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
total
Assessed
2y ago

Exploit prediction

1.40% chance of exploitation in the next 30 days, higher than 72% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N

Affected products

  • 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
  • Mitsubishi Electric Corporation MELSEC iQ-R series SIL2 Process CPU R32PSFCPU
  • Mitsubishi Electric Corporation MELSEC iQ-R series SIL2 Process CPU R120PSFCPU
  • mitsubishielectric melsec_iq-r08sfcpu
  • mitsubishielectric r16sfcpu
  • mitsubishielectric r32sfcpu
  • mitsubishielectric r120sfcpu
  • mitsubishielectric r08psfcpu
  • mitsubishielectric r16psfcpu
  • mitsubishielectric r32psfcpu
  • mitsubishielectric r120psfcpu

Classification

Weakness
  • CWE-319 Cleartext Transmission of Sensitive Information
  • CWE-639 Authorization Bypass Through User-Controlled Key

References

Sources

Fencer Intel 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.