CVE-2020-12834: eQ-3 Homematic Central Control Unit (CCU)2 through 2.51.6 and CCU3 through 3.51.6 allow Remote Code Execution

Q: How do I fix CVE-2020-12834?

homematic ccu2 firmware: upgrade to newer than 2.51.6; ccu3 firmware: upgrade to newer than 3.51.6. Exact commands for each OS are on this page.

Q: Is CVE-2020-12834 being exploited?

CVE-2020-12834 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-12834 affect?

CVE-2020-12834 affects homematic ccu2 firmware, ccu3 firmware. Severity is critical (CVSS 9.8). 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-logi

Q: How urgent is CVE-2020-12834?

Priority 68/100. Critical severity; EPSS top 4%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

This week

CRITICAL 9.8REMOTEUPGRADEUPGRADE

CVE-2020-12834 is a critical-severity flaw (CVSS 9.8) affecting homematic ccu2 firmware, ccu3 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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).

Why this priority

Critical severity
EPSS top 4%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	11.1% (top 4%)
CISA exploited list	No
Weakness	CWE-276
Published	2020-05-15
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: eq-3

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-05-15 17:15 UTCPublished CVE record published
2026-06-17 02:52 UTCUpdated Record last modified

eq-3 homematic ccu2 firmware UPGRADE

Affected: <= 2.51.6

Fixed in: newer than 2.51.6

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

eq-3 ccu3 firmware UPGRADE

Affected: <= 3.51.6

Fixed in: newer than 3.51.6

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-12834?

homematic ccu2 firmware: upgrade to newer than 2.51.6; ccu3 firmware: upgrade to newer than 3.51.6. Exact commands for each OS are on this page.

Is CVE-2020-12834 being exploited?

CVE-2020-12834 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-12834 affect?

CVE-2020-12834 affects homematic ccu2 firmware, ccu3 firmware. Severity is critical (CVSS 9.8). 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-logi

How urgent is CVE-2020-12834?

Priority 68/100. Critical severity; EPSS top 4%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-33032 CRITICAL 10.0 UPGRADE UPGRADE A Remote Code Execution (RCE) vulnerability in the WebUI component of the eQ-3 HomeMatic CCU2 firmware up to a
CVE-2019-9585 CRITICAL 9.8 UPGRADE UPGRADE eQ-3 Homematic CCU2 prior to 2.47.10 and CCU3 prior to 3.47.10 JSON API has Improper Access Control for Interf
CVE-2019-9584 CRITICAL 9.8 UPGRADE UPGRADE eQ-3 Homematic AddOn 'CloudMatic' on CCU2 and CCU3 allows uncontrolled admin access, resulting in the ability
CVE-2019-9583 HIGH 8.2 MITIGATE MITIGATE eQ-3 Homematic CCU2 and CCU3 obtain session IDs without login
CVE-2019-9582 HIGH 7.5 MITIGATE eQ-3 Homematic CCU2 outdated base software packages allows Denial of Service

References

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