CVE-2020-15798Network attack vector

Unauthenticated device control via credential-free Telnet

Published Feb 9, 2021 · Updated Jun 2, 2026

Missing authentication in Siemens HMI firmware allows remote attackers to gain full device access through an enabled Telnet service. The Telnet service accepts remote connections without requesting credentials and permits commands to execute in SYSTEM context. Telnet is disabled by default and must be enabled by a system integrator; successful access permits code execution and device control.

CVSS severity8.1
High
EPSS probability5.22%
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

Missing authentication in Siemens HMI firmware allows remote attackers to gain full device access through an enabled Telnet service. The Telnet service accepts remote connections without requesting credentials and permits commands to execute in SYSTEM context. Telnet is disabled by default and must be enabled by a system integrator; successful access permits code execution and device control.

The record

CVE
CVE-2020-15798
Published
Feb 9, 2021
Updated
Jun 2, 2026
Vendor
Siemens
Product
SINAMICS GM150 (with option X30)
Classifications
CWE-306, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Jun 2, 2026Record 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=All versions

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · SINAMICS GM150 (with option X30)version=All versions
Siemens · SINAMICS GH150version=All versions
Siemens · SINAMICS SL150version=All versions
Siemens · SINAMICS SM120version=All versions
Siemens · SIMATIC HMI Comfort Panelsversion=All versions < V16 Update 3a
Siemens · SINAMICS SM150iversion=All versions
Siemens · SINAMICS GL150 (with option X30)version=All versions
Siemens · SINAMICS SM150version=All versions
Siemens · SINAMICS SH150version=All versions
Siemens · SIMATIC HMI KTP Mobile Panelsversion=All versions < V16 Update 3a

Published CVSS scores

8.1Siemens ProductCERTCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8Zero Day InitiativeCVSS: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-306Missing Authentication for Critical Function
T1190Exploit Public-Facing Application

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