CVE-2020-28397Network attack vector

Unauthenticated PLC variable disclosure via authorization bypass

Published Aug 10, 2021 · Updated Aug 4, 2024

Incorrect authorization in Siemens SIMATIC controllers allows remote attackers to read protected PLC program variables over TCP port 102. The affected component permits multiple-attribute reads to return variables without enforcing authorization, exposing program data while leaving integrity and availability unchanged. No credentials or user interaction are required, and Siemens documents affected firmware ranges across the listed controller families and PLCSIM software.

CVSS severity5.3
Medium
EPSS probability0.75%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in Siemens SIMATIC controllers allows remote attackers to read protected PLC program variables over TCP port 102. The affected component permits multiple-attribute reads to return variables without enforcing authorization, exposing program data while leaving integrity and availability unchanged. No credentials or user interaction are required, and Siemens documents affected firmware ranges across the listed controller families and PLCSIM software.

The record

CVE
CVE-2020-28397
Published
Aug 10, 2021
Updated
Aug 4, 2024
Vendor
Siemens
Product
SIMATIC S7-1500 CPU
Classifications
CWE-863, T1005
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 10, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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?

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

  1. Affected versionversion=All versions > V2.5 < V2.9.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIMATIC S7-1500 CPUversion=All versions > V2.5 < V2.9.2
Siemens · SIMATIC ET 200SP Open Controller CPU 1515SP PC2version=All versions < V21.9
Siemens · TIM 1531 IRCversion=Version V2.1
Siemens · SIMATIC S7-PLCSIM Advancedversion=All versions > V2 < V4
Siemens · SIMATIC S7-1500 Software Controllerversion=All versions > V2.5 < V21.9
Siemens · SIMATIC S7-1200version=Version V4.4
Siemens · SIMATIC Drive Controllerversion=All versions < V2.9.2

Published CVSS scores

5.3Siemens ProductCERTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
5.0NVDAV:N/AC:L/Au:N/C:P/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-863Incorrect Authorization
T1005Data from Local System

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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