HOMEVULNERABILITIESCVE-2020-5657
MEDIUM

CVE-2020-5657

CWE-88Published: November 2, 2020· Updated: Jun 17, 2026

6.5
CVSS v3.1

Official Description

Improper neutralization of argument delimiters in a command ('Argument Injection') vulnerability in TCP/IP function included in the firmware of MELSEC iQ-R series (RJ71EIP91 EtherNet/IP Network Interface Module First 2 digits of serial number are '02' or before, RJ71PN92 PROFINET IO Controller Module First 2 digits of serial number are '01' or before, RD81DL96 High Speed Data Logger Module First 2 digits of serial number are '08' or before, RD81MES96N MES Interface Module First 2 digits of serial number are '04' or before, and RD81OPC96 OPC UA Server Module First 2 digits of serial number are '04' or before) allows unauthenticated attackers on adjacent network to stop the network functions of the products via a specially crafted packet.

NVD Source

Technical Analysis

CVE-2020-5657 requires adjacent network access, limiting remote exploitation but still posing risk in shared or local network environments.

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 6.5.

CVSS v3.1 Vector Breakdown

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

Affected Vendors & Products

mitsubishielectric10 product(s)
melsec iq-rj71eip91 firmwaremelsec iq-rj71eip91melsec iq-rj71pn92 firmwaremelsec iq-rj71pn92melsec iq-rd81dl96 firmwaremelsec iq-rd81dl96melsec iq-rd81mes96n firmwaremelsec iq-rd81mes96nmelsec iq-rd81opc96 firmwaremelsec iq-rd81opc96
Source: NVD CPE · 10 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
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Official Patches & Advisories

All References (6)

Quick Facts

CVE IDCVE-2020-5657
CVSS Score6.5 / 10
SeverityMEDIUM
WeaknessCWE-88
CISA KEVNo
Affected1 vendor(s)
PublishedNov 2, 2020

Related CVEs (CWE-88)

Recommended Actions

  • Apply vendor patches immediately
  • Monitor CVE-2020-5657 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.