HOMEVULNERABILITIESCVE-2021-20612
HIGH

CVE-2021-20612

NVD-CWE-OtherPublished: January 14, 2022· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official Description

Lack of administrator control over security vulnerability in MELSEC-F series FX3U-ENET Firmware version 1.14 and prior, FX3U-ENET-L Firmware version 1.14 and prior and FX3U-ENET-P502 Firmware version 1.14 and prior allows a remote unauthenticated attacker to cause a denial-of-service (DoS) condition in communication function of the product or other unspecified effects by sending specially crafted packets to an unnecessary opening of TCP port. Control by MELSEC-F series PLC is not affected by this vulnerability, but system reset is required for recovery.

NVD Source

Technical Analysis

CVE-2021-20612 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 availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

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

Affected Vendors & Products

mitsubishielectric6 product(s)
fx3u-enet firmwarefx3u-enetfx3u-enet-l firmwarefx3u-enet-lfx3u-enet-p502 firmwarefx3u-enet-p502
Source: NVD CPE · 6 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/JVNVU93268332/index.html
ADVISORYhttps://www.cisa.gov/uscert/ics/advisories/icsa-22-013-01
ADVISORYhttps://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-023_en.pdf
ADVISORYhttps://jvn.jp/vu/JVNVU93268332/index.html
ADVISORYhttps://www.cisa.gov/uscert/ics/advisories/icsa-22-013-01
ADVISORYhttps://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-023_en.pdf

All References (6)

→
https://jvn.jp/vu/JVNVU93268332/index.htmlThird Party Advisory · VDB Entry
→
https://www.cisa.gov/uscert/ics/advisories/icsa-22-013-01Third Party Advisory · US Government Resource
→
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-023_en.pdfVendor Advisory
→
https://jvn.jp/vu/JVNVU93268332/index.htmlThird Party Advisory · VDB Entry
→
https://www.cisa.gov/uscert/ics/advisories/icsa-22-013-01Third Party Advisory · US Government Resource
→
https://www.mitsubishielectric.com/en/psirt/vulnerability/pdf/2021-023_en.pdfVendor Advisory

Quick Facts

CVE IDCVE-2021-20612
CVSS Score7.5 / 10
SeverityHIGH
WeaknessNVD-CWE-Other
CISA KEVNo
Affected1 vendor(s)
PublishedJan 14, 2022

Related CVEs (NVD-CWE-Other)

CVE-2002-1468
10.0
CVE-1999-0745
10.0
CVE-2001-1080
10.0
CVE-1999-1405
10.0
CVE-2002-0747
10.0
CVE-1999-0789
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-20612 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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