CVE-2021-27389Network attack vector

Unauthenticated malicious code signing via exposed private key

Published Apr 22, 2021 · Updated Aug 3, 2024

Code-signing trust vulnerability in Siemens Opcenter Quality before V12.2 and QMS Automotive before V12.30 allows remote attackers to sign malicious executables. The SmartClient ClickOnce installers shipped a trusted but expired code-signing certificate whose private key was inadequately protected, allowing certificate spoofing and trusted signatures. No authentication is required to abuse the exposed key, and successful misuse can make attacker-controlled software appear trusted to downstream users or systems.

CVSS severity9.8
Critical
EPSS probability1.03%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code-signing trust vulnerability in Siemens Opcenter Quality before V12.2 and QMS Automotive before V12.30 allows remote attackers to sign malicious executables. The SmartClient ClickOnce installers shipped a trusted but expired code-signing certificate whose private key was inadequately protected, allowing certificate spoofing and trusted signatures. No authentication is required to abuse the exposed key, and successful misuse can make attacker-controlled software appear trusted to downstream users or systems.

The record

CVE
CVE-2021-27389
Published
Apr 22, 2021
Updated
Aug 3, 2024
Vendor
Siemens
Product
IBS QMS Automotive
Classifications
CWE-321, T1587.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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 < V12.30

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Siemens · IBS QMS Automotiveversion=All versions < V12.30
Siemens · Opcenter Qualityversion=All versions < V12.2

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

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-321Use of Hard-coded Cryptographic Key
T1587.003Code Signing Certificates

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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