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Homematic Ccu2 FirmwareOperating system · Eq 3

CVE-2021-33032

CRITICAL · 10.0 CVSS v3.1 Published 2021-07-22
Fix available
A fix is available. Upgrade to after 3.57.5 or later.
See remediation →
100/100
Remediation priority · Urgent
High EPSS Public exploit 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
A Remote Code Execution (RCE) vulnerability in the WebUI component of the eQ-3 HomeMatic CCU2 firmware up to and including version 2.57.5 and CCU3 firmware up to and including version 3.57.5 allows remote unauthenticated attackers to execute system commands as root via a simple HTTP request.

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 · high confidence

The eQ-3 HomeMatic CCU2 and CCU3 home automation controllers contain an unauthenticated remote code execution vulnerability in their WebUI component. Attackers can execute arbitrary system commands as root by sending a simple HTTP request to the WebUI, requiring no authentication. This affects CCU2 firmware up to 2.57.5 and CCU3 firmware up to 3.57.5.

MitigationUpdate the CCU2 firmware to version 2.57.6 or later and CCU3 firmware to version 3.57.6 or later to patch the vulnerability. If patching is not immediately possible, restrict network access to the WebUI interface to trusted IP addresses only.

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
Homematic Ccu2 FirmwareOperating system
Affected:<= 2.57.5
Homematic Ccu3 FirmwareOperating system
Affected:<= 3.57.5

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
Changed
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 device model
    Access the CCU WebUI and check the system information page, or run the command 'cat /proc/cpuinfo' via SSH if available to confirm whether the device is a CCU2 or CCU3
    Affected if The device is an eQ-3 HomeMatic CCU2 or CCU3 controller
  2. Check the installed firmware version
    In the WebUI, navigate to Status and Control > System Information to view the firmware version, or access the 'eq3config.cgi' endpoint or check the version file typically located at /usr/local/etc/version if SSH is available
    Affected if The firmware version is 2.57.5 or earlier for CCU2, or 3.57.5 or earlier for CCU3
  3. Confirm WebUI accessibility
    Attempt to access the WebUI login page at the device IP address using HTTP (port 80) or HTTPS (port 443) from the network
    Affected if The WebUI is reachable over the network without authentication required
  4. Verify the command execution interface exists
    Check if the ReGaHss RPC or TCL scripting interface responds to unauthenticated requests by sending a test HTTP request to the WebUI endpoint (note: this is the vulnerable attack surface)
    Affected if The WebUI accepts and processes requests without requiring authentication credentials

A user is affected if they are running a CCU2 device on firmware 2.57.5 or earlier, or a CCU3 device on firmware 3.57.5 or earlier, with the WebUI exposed on the network.

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 a release after 3.57.5
Interim mitigation

Update the CCU2 firmware to version 2.57.6 or later and CCU3 firmware to version 3.57.6 or later to patch the vulnerability. If patching is not immediately possible, restrict network access to the WebUI interface to trusted IP addresses only.

Recommended fix Moderate confidence

CCU2 firmware > 2.57.5, CCU3 firmware > 3.57.5 (check eq-3.com for latest stable release)

  1. Check the current firmware version of the Homematic CCU2 or CCU3 device through the WebUI or device status
  2. Visit the official eQ-3 download page at www.eq-3.com to obtain the latest firmware version
  3. Download the appropriate firmware update file for your device model
  4. Access the WebUI of the CCU device and navigate to the Firmware Update section
  5. Upload and apply the firmware update following the vendor's documented update procedure
  6. After the update completes, verify the new firmware version is installed and confirm the WebUI is accessible
  7. Ensure the device is not directly exposed to the internet; restrict network access to trusted networks only
Caveat Review eQ-3 release notes for any changes to functionality or required reconfiguration after firmware upgrade

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

Fix this in Homematic Ccu2 Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
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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-2021-33032 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data