CVE-2020-5527Network attack vector

Ethernet communication outage via UDP resource exhaustion

Published Mar 30, 2020 · Updated Aug 4, 2024

Uncontrolled resource consumption in MELSOFT Transmission Port on Mitsubishi Electric MELSEC PLCs allows remote attackers to block communications. The UDP/IP port continues consuming resources while accepting a massive volume of data until it can no longer process client traffic. Network access to an Ethernet-equipped controller is sufficient; sequential control remains operational, and communications recover after the traffic stops.

CVSS severity7.5
High
EPSS probability1.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in MELSOFT Transmission Port on Mitsubishi Electric MELSEC PLCs allows remote attackers to block communications. The UDP/IP port continues consuming resources while accepting a massive volume of data until it can no longer process client traffic. Network access to an Ethernet-equipped controller is sufficient; sequential control remains operational, and communications recover after the traffic stops.

The record

CVE
CVE-2020-5527
Published
Mar 30, 2020
Updated
Aug 4, 2024
Vendor
Mitsubishi Electric Corporation
Product
MELSOFT Transmission Port (UDP/IP)
Classifications
CWE-400, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 30, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=MELSEC iQ-R series (all versions), MELSEC iQ-F series (all versions), MELSEC Q series (all versions), MELSEC L series (all versions), and MELSEC F series (all versions)

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mitsubishi Electric Corporation · MELSOFT Transmission Port (UDP/IP)version=MELSEC iQ-R series (all versions), MELSEC iQ-F series (all versions), MELSEC Q series (all versions), MELSEC L series (all versions), and MELSEC F series (all versions)

Published CVSS scores

5.3JPCERT/CCCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
5.0JPCERT/CCAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T0814Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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