HOMEVULNERABILITIESCVE-2021-20597
CRITICAL

CVE-2021-20597

CWE-522Published: August 6, 2021· Updated: Jun 17, 2026

9.1
CVSS v3.1

Official Description

Insufficiently Protected Credentials vulnerability in Mitsubishi Electric MELSEC iQ-R series Safety CPU modules R08/16/32/120SFCPU firmware versions "26" and prior and Mitsubishi Electric MELSEC iQ-R series SIL2 Process CPU modules R08/16/32/120PSFCPU firmware versions "11" and prior allows a remote unauthenticated attacker to login to the target unauthorizedly by sniffing network traffic and obtaining credentials when registering user information in the target or changing a password.

NVD Source

Technical Analysis

CVE-2021-20597 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), with a CVSS base score of 9.1.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected Vendors & Products

mitsubishielectric16 product(s)
r08sfcpu firmwarer08sfcpur16sfcpu firmwarer16sfcpur32sfcpu firmwarer32sfcpur120sfcpu firmwarer120sfcpur08psfcpu firmwarer08psfcpur16psfcpu firmwarer16psfcpu+4
Source: NVD CPE · 16 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://jvn.jp/vu/JVNVU98578731/index.html
ADVISORYhttps://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-009_en.pdf
ADVISORYhttps://jvn.jp/vu/JVNVU98578731/index.html
ADVISORYhttps://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-009_en.pdf

All References (6)

→
https://jvn.jp/vu/JVNVU98578731/index.htmlThird Party Advisory
→
https://www.cisa.gov/uscert/ics/advisories/icsa-21-250-01
→
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-009_en.pdfVendor Advisory
→
https://jvn.jp/vu/JVNVU98578731/index.htmlThird Party Advisory
→
https://www.cisa.gov/uscert/ics/advisories/icsa-21-250-01
→
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-009_en.pdfVendor Advisory

Quick Facts

CVE IDCVE-2021-20597
CVSS Score9.1 / 10
SeverityCRITICAL
WeaknessCWE-522
CISA KEVNo
Affected1 vendor(s)
PublishedAug 6, 2021

Related CVEs (CWE-522)

CVE-2024-12799
10.0
CVE-2026-29128
10.0
CVE-2019-1384
9.9
CVE-2025-0867
9.9
CVE-2026-56843
9.9
CVE-2021-36783
9.9

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-20597 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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