What is the CVSS score of CVE-2021-20999?

CVE-2021-20999 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.9%.

Uc20 Wl2000 Ac Firmware CVE-2021-20999

CRITICAL

Exposure of Resource to Wrong Sphere (CWE-668)

2021-05-13 info@cert.vde.com

Information Disclosure Uc20 Wl2000 Ac Firmware Uc20 Wl2000 Iot Firmware Iot Gw30 Firmware Iot Gw30 4G Eu Firmware Weidmueller

9.8

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-668 OWASP Top 10:2025 A01:2025 - Broken Access Control ASVS 5.0 V8 - Authorization Resource sphere isolation MITRE ATT&CK 1 technique across 1 tactic: Collection The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required.
Exploit ScenarioDerived	A remote attacker could access resources from an unintended security context by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.

No patch listed yet 0.9% exploitation probability (EPSS)

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AnalysisAI

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. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Implement proper access controls, validate resource access permissions, use security boundaries.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Exposure of Resource to Wrong Sphere (CWE-668), which allows attackers to access resources from an unintended security context. 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. Affected products include: Weidmueller Uc20-Wl2000-Ac Firmware, Weidmueller Uc20-Wl2000-Iot Firmware, Weidmueller Iot-Gw30 Firmware, Weidmueller Iot-Gw30-4G-Eu Firmware. Version information: up to 1.12.1.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionNVD

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.

Threat Intelligence Overview

EPSS Score

0.9%

Top 43% exploitable

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC No

EPSS 0.9%

Patch available No

Active threat No

Deciding rule

CRITICAL severity

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +1

CVSS: +49

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.