CVE-2023-0811Network attack vector

Engineering lockout via unauthenticated UM password overwrite

Published Mar 16, 2023 · Updated Jan 16, 2025

Improper access control in OMRON CJ1M CPU Units 4.0 and earlier allows remote attackers to overwrite the UM password via FINS. The controller accepts a PROGRAM AREA WRITE to the UM-password memory region without enforcing the intended access control. Unauthenticated network access to FINS is sufficient; changing the value can disable UM protection or set a non-keyboard password that blocks engineering access to the user program.

CVSS severity9.1
Critical
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in OMRON CJ1M CPU Units 4.0 and earlier allows remote attackers to overwrite the UM password via FINS. The controller accepts a PROGRAM AREA WRITE to the UM-password memory region without enforcing the intended access control. Unauthenticated network access to FINS is sufficient; changing the value can disable UM protection or set a non-keyboard password that blocks engineering access to the user program.

The record

CVE
CVE-2023-0811
Published
Mar 16, 2023
Updated
Jan 16, 2025
Vendor
OMRON Corporation
Product
SYSMAC CJ-series CJ1M CPU Units
Classifications
CWE-284, T0855
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 16, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 16, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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  1. Affected versionversion=All versions

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

OMRON Corporation · SYSMAC CJ-series CJ1M CPU Unitsversion=All versions

Published CVSS scores

9.1ICS-CERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.

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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-284Improper Access Control
T0855Unauthorized Command Message

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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