dbcve.org
Homematic Ccu2 FirmwareOperating system · Eq 3

CVE-2020-12834

CRITICAL · 9.8 CVSS v3.1 Published 2020-05-15
Fix available
A fix is available. Upgrade to after 3.51.6 or later.
See remediation →
100/100
Remediation priority · Urgent
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
eQ-3 Homematic Central Control Unit (CCU)2 through 2.51.6 and CCU3 through 3.51.6 allow Remote Code Execution in the JSON API Method ReGa.runScript, by unauthenticated attackers with access to the web interface, due to the default auto-login feature being enabled during first-time setup (or factory reset).

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
How this class of weakness works · CWE-276

Files, directories, or resources ship with permissions more open than they need to be, so unintended users can read or modify them. Attackers look for exactly these loose defaults. Remediation means tightening permissions to the minimum required and verifying them at install and at runtime.

General guidance for the incorrect default permissions class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

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:<= 2.51.6
Ccu3 FirmwareOperating system
Affected:<= 3.51.6

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

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 3.51.6
Recommended fix Moderate confidence

CCU2: firmware > 2.51.6 | CCU3: firmware > 3.51.6 (obtain exact latest version from eQ-3)

  1. 1. Identify the current firmware version of the Homematic CCU2 or CCU3 device via the web interface (Status > System Information)
  2. 2. If running CCU2 firmware <= 2.51.6 or CCU3 firmware <= 3.51.6, the device is vulnerable
  3. 3. Check the vendor (eQ-3) website or the Homematic forum for the latest available firmware version that addresses this vulnerability
  4. 4. Backup the current device configuration via the web interface (Settings > Backup & Restore)
  5. 5. Update the firmware to the latest available version from eQ-3 that is newer than 2.51.6 for CCU2 or 3.51.6 for CCU3
  6. 6. After firmware update, access the web interface and navigate to Settings > Security > User Administration
  7. 7. Verify that the auto-login feature is disabled and configure proper authentication for the web interface
  8. 8. Confirm the vulnerability is remediated by attempting to access the ReGa.runScript API endpoint without authentication
Caveat Firmware updates on Homematic devices typically preserve configuration but should be performed during maintenance windows as the CCU will restart; ensure backup is available before proceeding

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

We can identify the exact fixed release, upgrade, and verify it in staging — typical engagement from $1,600. Get the upgrade done

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2020-12834 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2020-12834 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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