CVE-2023-27396Network attack vector

Controller command execution via unauthenticated FINS messages

Published Jun 19, 2023 · Updated Dec 24, 2024

Authentication bypass in OMRON SYSMAC CPU units allows remote attackers to read data or execute controller commands over FINS. The FINS receiver processes plaintext command codes and parameters without encryption, data-authenticity checks, or sender authentication. Network access to FINS is sufficient; exposed operations include I/O, parameter, and program writes, mode changes, file operations, and forced set or reset.

CVSS severity9.8
Critical
EPSS probability1.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in OMRON SYSMAC CPU units allows remote attackers to read data or execute controller commands over FINS. The FINS receiver processes plaintext command codes and parameters without encryption, data-authenticity checks, or sender authentication. Network access to FINS is sufficient; exposed operations include I/O, parameter, and program writes, mode changes, file operations, and forced set or reset.

The record

CVE
CVE-2023-27396
Published
Jun 19, 2023
Updated
Dec 24, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-799, CWE-345, CWE-290, CWE-412, CWE-400, CWE-319, CWE-294, CWE-306, T1692.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 19, 2023CVE publishedPublication date reported by the CVE source.
  2. Dec 24, 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

9.8NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 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-799Improper Control of Interaction Frequency
CWE-345Insufficient Verification of Data Authenticity
CWE-290Authentication Bypass by Spoofing
CWE-412Unrestricted Externally Accessible Lock
CWE-400Uncontrolled Resource Consumption
CWE-319Cleartext Transmission of Sensitive Information
CWE-294Authentication Bypass by Capture-replay
CWE-306Missing Authentication for Critical Function
T1692.001Unauthorized Message: Command Message

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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