dbcve.org
Kr C4 FirmwareOperating system · Kuka

CVE-2021-33016

CRITICAL · 9.8 CVSS v3.1 Published 2022-05-26
Fix available
A fix is available. Upgrade to 8.7 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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 full access (read/write/delete) to sensitive folders due to hard-coded credentials on 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

The KUKA KR C4 control software and any product running KSS (KUKA System Software) versions prior to 8.7 contain hard-coded credentials that allow an attacker to bypass authentication and gain full read/write/delete access to sensitive folders on the control system.

MitigationUpgrade KUKA KR C4 control software to version 8.7 or later. If immediate patching is not feasible, isolate the affected systems on a restricted network and monitor for unauthorized access attempts.

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
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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 KUKA KR C4 Firmware version
    Access the robot controller HMI or use the KUKA system information panel. Navigate to Start-up > Service > System Info or check the boot screen for the firmware version number.
    Affected if The displayed firmware version is lower than 8.7 (for example, 8.5, 8.6, or any version < 8.7)
  2. Identify KSS (KUKA System Software) version
    Access the controller operating system via the teach pendant or login to the Windows-based controller. Look for system information or version details in the KUKA software menu.
    Affected if Any KSS version is installed, as all versions are affected according to the vulnerability disclosure.
  3. Determine if network services are enabled
    Check the controller network configuration and running services. Look for exposed ports (common industrial protocols like OPC-UA, Ethernet/IP, or KUKA's remote access services) in the network settings.
    Affected if The control system has enabled network connectivity or remote access services that could allow an external attacker to reach the authentication mechanism.
  4. Review network segmentation and access controls
    Examine the network topology to determine if the KUKA controller is isolated on a dedicated industrial network or if it shares network segments with corporate systems or the internet.
    Affected if The controller is directly accessible from broader network segments without firewall or VLAN isolation.

Your environment is affected if the KUKA KR C4 Firmware version is below 8.7 OR any version of KSS is running, and the controller has network accessibility that could permit an attacker to leverage the hard-coded credentials for unauthorized access.

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

Upgrade KUKA KR C4 control software to version 8.7 or later. If immediate patching is not feasible, isolate the affected systems on a restricted network and monitor for unauthorized access attempts.

Recommended fix High confidence

KUKA KR C4 Firmware version 8.7 or later

  1. Upgrade KUKA KR C4 Firmware to version 8.7 or later
  2. Verify that the KSS (KUKA System Software) is also updated to a version compatible with the firmware 8.7 release
  3. After upgrade, change any default credentials that may have been hard-coded and implement strong, unique credentials
  4. Test the system to confirm full access controls are functioning properly
  5. Review KUKA security documentation for any additional post-upgrade hardening recommendations
Caveat Industrial control system firmware upgrades may require controller restart and should be performed during planned maintenance windows; verify application compatibility before deployment

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

Fix this in Kr C4 Firmware Scoped from the published advisory
  • Consultation8.0 h
  • Implementation4.0 h
  • Testing12.0 h
  • Review / QA6.0 h
30.0 hours of engineering $5,200
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $8,320.

Scan for this in your stack

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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-2021-33016 in production — separate from our analysis above.

No notes yet

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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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data