CVE-2021-37172Network attack vector

Unauthenticated program download via password validation failure

Published Aug 10, 2021 · Updated Aug 4, 2024

Improper authentication in Siemens SIMATIC S7-1200 V4.5.0 allows remote attackers to download arbitrary PLC programs over the network. A CPU provisioned with TIA Portal V13 fails to validate configured access-level passwords when later contacted through TIA Portal, so it accepts a program download without the required credential. The flaw is limited to firmware V4.5.0 provisioned with the original V13 release; V13 SP1 or later provisioning does not create the vulnerable state.

CVSS severity7.5
High
EPSS probability0.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Improper authentication in Siemens SIMATIC S7-1200 V4.5.0 allows remote attackers to download arbitrary PLC programs over the network. A CPU provisioned with TIA Portal V13 fails to validate configured access-level passwords when later contacted through TIA Portal, so it accepts a program download without the required credential. The flaw is limited to firmware V4.5.0 provisioned with the original V13 release; V13 SP1 or later provisioning does not create the vulnerable state.

The record

CVE
CVE-2021-37172
Published
Aug 10, 2021
Updated
Aug 4, 2024
Vendor
Siemens
Product
SIMATIC S7-1200
Classifications
CWE-287, T0889
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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=V4.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SIMATIC S7-1200version=V4.5.0

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/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-287Improper Authentication
T0889Modify Program

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo