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Kr C4 FirmwareOperating system · Kuka

CVE-2021-33014

HIGH · 8.8 CVSS v3.1 Published 2022-05-26
Fix available
A fix is available. Upgrade to 8.7 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An attacker can gain VxWorks Shell after login due to hard-coded credentials on a KUKA KR C4 control software for versions prior to 8.7 or any product running KSS.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Hard-coded credentials in KUKA KR C4 control software (KSS) versions prior to 8.7 create an unauthorized backdoor allowing attackers to access the VxWorks Shell after login. This is a direct authentication bypass vulnerability exploiting embedded credentials in the industrial control system software.

MitigationUpdate KUKA KR C4 control software to version 8.7 or later, or obtain vendor-provided patches for any KSS-running products. Immediately restrict network access to the control system interface as a compensating control.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Kr C4 FirmwareOperating system
Affected:< 8.7
KssOperating system
Affected:all versions

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the KUKA KR C4 firmware version
    Access the KUKA HMI (SmartHMI) and navigate to the System or About section to view the installed KSS (KUKA System Software) version. Alternatively, check the controller's system information screen or consult the system documentation for the installed firmware version.
    Affected if The KSS firmware version is below 8.7, or the KSS version cannot be determined and the firmware is not confirmed at 8.7 or later.
  2. Verify if VxWorks Shell is enabled or accessible
    Check the controller configuration or service settings to determine if the VxWorks Shell service is running and accessible. Look for VxWorks-related services, ports, or remote access features in the KUKA system configuration.
    Affected if The VxWorks Shell is enabled and accessible on the controller, providing an interface that could be targeted by the hardcoded credentials.
  3. Review network exposure of the control system
    Examine network firewall rules, access control lists, or VLAN configuration surrounding the KUKA controller to determine if the control system interface is exposed to untrusted networks. Check if ports or services associated with the VxWorks Shell are reachable from outside the trusted zone.
    Affected if The controller or its VxWorks Shell service is reachable from network segments that are not fully trusted or controlled.
  4. Confirm the presence of hardcoded credentials
    Review any documented or undocumented service accounts, backdoor accounts, or default credentials in the controller configuration or system documentation. Check for accounts not created by the facility administrator.
    Affected if There are undocumented or default credentials present in the system that were not provisioned by the system administrator.

A user is affected if the KUKA KR C4 firmware version is below 8.7 (or the KSS version cannot be verified as 8.7 or later) AND the VxWorks Shell is accessible on the controller.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 8.7 or later
Fixed in 8.7
Interim mitigation

Update KUKA KR C4 control software to version 8.7 or later, or obtain vendor-provided patches for any KSS-running products. Immediately restrict network access to the control system interface as a compensating control.

Recommended fix Moderate confidence

Kr C4 Firmware version 8.7 or later

  1. 1. Identify the current Kr C4 firmware version by accessing the controller's system information or checking the pendant interface
  2. 2. Verify if the current version is below 8.7
  3. 3. Contact KUKA customer support or your authorized KUKA service partner to obtain the firmware version 8.7 or later update
  4. 4. Follow KUKA's official firmware upgrade procedure, which typically requires the controller to be in maintenance mode
  5. 5. After upgrade, verify that the hard-coded credentials have been removed or changed
  6. 6. For KSS (KUKA System Software), contact KUKA to confirm if a separate patch or update is required since all KSS versions are reportedly affected

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Kr C4 Firmware Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing8.0 h
  • Review / QA4.0 h
30.0 hours of engineering $5,280
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2021-33014 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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