CVE-2021-20999: In Weidmüller u-controls and IoT-Gateways in versions up to 1.12.1 a network port intended only for device-int

Q: How do I fix CVE-2021-20999?

uc20-wl2000-ac firmware: upgrade to 1.9.1, 1.10.3; uc20-wl2000-iot firmware: upgrade to 1.9.1, 1.10.3; iot-gw30 firmware: upgrade to 1.9.1, 1.10.3. Exact commands for each OS are on this page.

Q: Is CVE-2021-20999 being exploited?

CVE-2021-20999 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-2021-20999 affect?

CVE-2021-20999 affects uc20-wl2000-ac firmware, uc20-wl2000-iot firmware, iot-gw30 firmware. Severity is critical (CVSS 9.4). In Weidmüller u-controls and IoT-Gateways in versions up to 1.12.1 a network port intended only for device-internal usage is accidentally accessible via external network interfaces. By exploiting this vulnerability the device may be manipul

Q: How urgent is CVE-2021-20999?

Priority 53/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.4REMOTEUPGRADEUPGRADEUPGRADE

CVE-2021-20999 is a critical-severity flaw (CVSS 9.4) affecting uc20-wl2000-ac firmware, uc20-wl2000-iot firmware, iot-gw30 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Weidmüller u-controls and IoT-Gateways in versions up to 1.12.1 a network port intended only for device-internal usage is accidentally accessible via external network interfaces. By exploiting this vulnerability the device may be manipulated or the operation may be stopped.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.4 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 39%)
CISA exploited list	No
Weakness	CWE-668
Published	2021-05-13
Last modified	2026-06-17

Publisher (CNA): CERT VDE · Vendor: weidmueller

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

Am I affected?

Timeline

2021-05-13 14:15 UTCPublished CVE record published
2026-06-17 03:34 UTCUpdated Record last modified

weidmueller uc20-wl2000-ac firmware UPGRADE

Affected: >= 1.3.0 and < 1.9.1 · >= 1.10.0 and < 1.10.3 · 1.11.0 · 1.12.1

Fixed in: 1.9.1, 1.10.3

Safe to downgrade to: a release before 1.3.0

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.

weidmueller uc20-wl2000-iot firmware UPGRADE

Affected: >= 1.3.0 and < 1.9.1 · >= 1.10.0 and < 1.10.3 · 1.11.0 · 1.12.1

Fixed in: 1.9.1, 1.10.3

Safe to downgrade to: a release before 1.3.0

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.

weidmueller iot-gw30 firmware UPGRADE

Affected: >= 1.3.0 and < 1.9.1 · >= 1.10.0 and < 1.10.3 · 1.11.0 · 1.12.1

Fixed in: 1.9.1, 1.10.3

Safe to downgrade to: a release before 1.3.0

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.

weidmueller iot-gw30-4g-eu firmware UPGRADE

Affected: >= 1.3.0 and < 1.9.1 · >= 1.10.0 and < 1.10.3 · 1.11.0 · 1.12.1

Fixed in: 1.9.1, 1.10.3

Safe to downgrade to: a release before 1.3.0

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-2021-20999?

uc20-wl2000-ac firmware: upgrade to 1.9.1, 1.10.3; uc20-wl2000-iot firmware: upgrade to 1.9.1, 1.10.3; iot-gw30 firmware: upgrade to 1.9.1, 1.10.3. Exact commands for each OS are on this page.

Is CVE-2021-20999 being exploited?

CVE-2021-20999 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-2021-20999 affect?

CVE-2021-20999 affects uc20-wl2000-ac firmware, uc20-wl2000-iot firmware, iot-gw30 firmware. Severity is critical (CVSS 9.4). In Weidmüller u-controls and IoT-Gateways in versions up to 1.12.1 a network port intended only for device-internal usage is accidentally accessible via external network interfaces. By exploiting this vulnerability the device may be manipul

How urgent is CVE-2021-20999?

Priority 53/100. Critical severity; Remotely exploitable, no login, no user action

References

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