CVE-2021-20609Network attack vector

Remote service interruption via crafted Ethernet packets

Published Dec 1, 2021 · Updated Aug 3, 2024

Uncontrolled resource consumption in Mitsubishi Electric MELSEC and MELIPC Ethernet ports allows remote attackers to halt operations. The embedded Ethernet-port packet handler fails to bound resource use for specially crafted packets; the precise parsing error and exhausted resource are undisclosed. No authentication or user action is required, and exploitation can stop control-program execution or Ethernet communication until reset.

CVSS severity7.5
High
EPSS probability3.08%
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 Mitsubishi Electric MELSEC and MELIPC Ethernet ports allows remote attackers to halt operations. The embedded Ethernet-port packet handler fails to bound resource use for specially crafted packets; the precise parsing error and exhausted resource are undisclosed. No authentication or user action is required, and exploitation can stop control-program execution or Ethernet communication until reset.

The record

CVE
CVE-2021-20609
Published
Dec 1, 2021
Updated
Aug 3, 2024
Vendor
Mitsubishi Electric Corporation
Product
MELSEC iQ-R Series R16ENCPU
Classifications
CWE-400, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=Firmware versions "57" and prior

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mitsubishi Electric Corporation · MELSEC iQ-R Series R16ENCPUversion=Firmware versions "57" and prior
Mitsubishi Electric Corporation · MELSEC Q Series Q170MSCPUversion=Operating system software version "Y" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R08SFCPUversion=Firmware versions "26" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R16SFCPUversion=Firmware versions "26" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q04UDPVCPUversion=The first 5 digits of serial No. "23071" and prior
Mitsubishi Electric Corporation · MELSEC-L Series L02CPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC-L Series L26CPU-PBTversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R32CPUversion=Firmware versions "57" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R120PSFCPUversion=Firmware versions "08" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R16CPUversion=Firmware versions "57" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R16PCPUversion=Firmware versions "29" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q50UDEHCPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R64MTCPUversion=Operating system software version "23" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q06UDEHCPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC Q Series MR-MQ100version=Operating system software version "F" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R120PCPUversion=Firmware versions "29" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q26DHCCPU-LSversion=The first 5 digits of serial No. "24031" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q10UDEHCPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC-L Series L26CPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R16PSFCPUversion=Firmware versions "08" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q24DHCCPU-VGversion=The first 5 digits of serial No. "24031" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R08PSFCPUversion=Firmware versions "08" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R32PCPUversion=Firmware versions "29" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R16MTCPUversion=Operating system software version "23" and prior
Mitsubishi Electric Corporation · MELSEC-L Series L02CPU-Pversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q24DHCCPU-LSversion=The first 5 digits of serial No. "24031" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q26UDVCPUversion=The first 5 digits of serial No. "23071" and prior
Mitsubishi Electric Corporation · MELIPC Series MI5122-VWversion=Firmware versions "05" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R00CPUversion=Firmware versions "24" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R120SFCPUversion=Firmware versions "26" and prior
Mitsubishi Electric Corporation · MELSEC Q Series Q170MCPUversion=Operating system software version "W" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q13UDVCPUversion=The first 5 digits of serial No. "23071" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q12DCCPU-Vversion=The first 5 digits of serial No. "24031" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R32MTCPUversion=Operating system software version "23" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R04ENCPUversion=Firmware versions "57" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q06UDVCPUversion=The first 5 digits of serial No. "23071" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q13UDEHCPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R08ENCPUversion=Firmware versions "57" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q04UDEHCPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R32ENCPUversion=Firmware versions "57" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R08CPUversion=Firmware versions "57" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q03UDVCPUversion=The first 5 digits of serial No. "23071" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q24DHCCPU-Vversion=The first 5 digits of serial No. "24031" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q13UDPVCPUversion=The first 5 digits of serial No. "23071" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R04CPUversion=Firmware versions "57" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R32PSFCPUversion=Firmware versions "08" and prior
Mitsubishi Electric Corporation · MELSEC-L Series L26CPU-Pversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R08PCPUversion=Firmware versions "29" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q03UDECPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC-L Series L06CPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC-L Series L26CPU-BTversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R01CPUversion=Firmware versions "24" and prior
Mitsubishi Electric Corporation · MELSEC Q Series Q170MSCPU-S1version=Operating system software version "Y" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q04UDVCPUversion=The first 5 digits of serial No. "23071" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R32SFCPUversion=Firmware versions "26" and prior
Mitsubishi Electric Corporation · MELSEC-L Series L06CPU-Pversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R12CCPU-Vversion=Firmware versions "16" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q06UDPVCPUversion=The first 5 digits of serial No. "23071" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q20UDEHCPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC Q Series Q173DSCPUversion=Operating system software version "Y" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q26UDPVCPUversion=The first 5 digits of serial No. "23071" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q100UDEHCPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC Q Series Q173DCPU-S1version=Operating system software version "W" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R120ENCPUversion=Firmware versions "57" and prior
Mitsubishi Electric Corporation · MELSEC-Q Series Q26UDEHCPUversion=The first 5 digits of serial No. "23121" and prior
Mitsubishi Electric Corporation · MELSEC Q Series Q172DSCPUversion=Operating system software version "Y" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R02CPUversion=Firmware versions "24" and prior
Mitsubishi Electric Corporation · MELSEC Q Series Q172DCPU-S1version=Operating system software version "W" and prior
Mitsubishi Electric Corporation · MELSEC iQ-R Series R120CPUversion=Firmware versions "57" and prior

Published CVSS scores

7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C
7.5Mitsubishi Electric CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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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