CVE-2021-27458Network attack vector

Ethernet service interruption via unreleased connections

Published Apr 19, 2021 · Updated Aug 3, 2024

Denial of service in all versions of JTEKT TOYOPUC products allows remote attackers to block Ethernet communications by holding connections open. The PLC fails to clear a connection that is disconnected incorrectly or deliberately left active, preventing the expected device from connecting. Only devices configured for TCP Destination Non-Specified Passive Open mode are exposed, and affected Ethernet communications remain unavailable until the PLC is restarted.

CVSS severityUnavailable
Unscored
EPSS probability1.10%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in all versions of JTEKT TOYOPUC products allows remote attackers to block Ethernet communications by holding connections open. The PLC fails to clear a connection that is disconnected incorrectly or deliberately left active, preventing the expected device from connecting. Only devices configured for TCP Destination Non-Specified Passive Open mode are exposed, and affected Ethernet communications remain unavailable until the PLC is restarted.

The record

CVE
CVE-2021-27458
Published
Apr 19, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-404, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 19, 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

7.2JTEKT CorporationCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:H/RL:O/RC:C

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-404Improper Resource Shutdown or Release
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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