CVE-2023-0027Network attack vector

Information disclosure via malformed response replay

Published Mar 17, 2023 · Updated Feb 26, 2025

Information disclosure in Rockwell Automation Modbus TCP Server AOI before 2.04.00 allows remote attackers to read connected-device data. A malformed Modbus request makes the controller replay its most recent response to a valid request instead of rejecting the input. The Server AOI must be running on a controller, and exploitation requires knowledge of the Modbus address used by that prior request.

CVSS severity5.3
Medium
EPSS probability0.85%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Rockwell Automation Modbus TCP Server AOI before 2.04.00 allows remote attackers to read connected-device data. A malformed Modbus request makes the controller replay its most recent response to a valid request instead of rejecting the input. The Server AOI must be running on a controller, and exploitation requires knowledge of the Modbus address used by that prior request.

The record

CVE
CVE-2023-0027
Published
Mar 17, 2023
Updated
Feb 26, 2025
Vendor
Rockwell Automation
Product
Modbus TCP Server Add-On Instruction
Classifications
CWE-200, T0866
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 26, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.00.00 - 2.00.03

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Rockwell Automation · Modbus TCP Server Add-On Instructionversion=2.00.00 - 2.00.03

Published CVSS scores

5.3Rockwell AutomationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
4.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

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-200Exposure of Sensitive Information to an Unauthorized Actor
T0866Exploitation of Remote Services

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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