CVE-2021-20592Network attack vector

Unauthenticated DoS via MODBUS connection churn

Published Aug 5, 2021 · Updated Aug 3, 2024

Missing synchronization in Mitsubishi Electric GOT2000 and GT SoftGOT2000 allows remote attackers to stop MODBUS/TCP slave communication. The communication handler fails to synchronize rapidly repeated connection and disconnection operations on the MODBUS/TCP port, exhausting or wedging the slave function. The attack requires no authentication but does require network reachability; GOT units need a restart or reset, while GT SoftGOT2000 must be restarted to restore service.

CVSS severity5.9
Medium
EPSS probability1.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing synchronization in Mitsubishi Electric GOT2000 and GT SoftGOT2000 allows remote attackers to stop MODBUS/TCP slave communication. The communication handler fails to synchronize rapidly repeated connection and disconnection operations on the MODBUS/TCP port, exhausting or wedging the slave function. The attack requires no authentication but does require network reachability; GOT units need a restart or reset, while GT SoftGOT2000 must be restarted to restore service.

The record

CVE
CVE-2021-20592
Published
Aug 5, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-820, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 5, 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

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.9Mitsubishi Electric CorporationCVSS:3.0/AV:N/AC:H/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.

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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-820Missing Synchronization
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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