CVE-2021-34580

MB connect line mbCONNECT24 — vulnerability CVE-2021-34580

In mymbCONNECT24, mbCONNECT24 <= 2.9.0 an unauthenticated user can enumerate valid backend users by checking what kind of response the server sends for crafted invalid login attempts.

CVSS 7.5Patch available

This record: live connection— last retrieved: 7 November 2026 at 04:38.

Vendors

MB connect line, Helmholz

Products

mbCONNECT24, mymbCONNECT24, myREX24, myREX24.virtual

up to version <=2.9.0

Published

27 October 2021

Last modified

17 June 2026

Original source information

Taken directly from NVD, CISA or the vendor — sometimes in English, unchanged from the source.

Technical description

In mymbCONNECT24, mbCONNECT24 <= 2.9.0 an unauthenticated user can enumerate valid backend users by checking what kind of response the server sends for crafted invalid login attempts.

CVSS 3.1 — vector details

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack vector

NETWORK

Privileges required

NONE

User interaction

NONE

Confidentiality

High

Integrity

None

Availability

None

EPSS — Exploit Prediction Scoring System

Probability of exploitation within 30 days

1.0%

Percentile

64e

Source: FIRST.org, updated on 6 November 2026.

Patch information

Update mbCONNECT24/mymbCONNECT24 to 2.10.1

IACS Radar assessment

Our own interpretation and context for the source data above.

IACS Radar assessment

Our own interpretation and context for this vulnerability — not an official source.

IACS Radar priority score

41/ 100

Based on CVSS 7.5, EPSS 1.0%, industrial relevance 40/100.

Combines CVSS, EPSS, KEV status, industrial relevance and exposure relevance — a complement to, not a replacement for, the individual scores below and above.

Conditions for exploitation

•Network access to the affected device or segment is required.
•No valid credentials are needed.
•No user interaction required.

Operational impact & energy relevance

Limited impact on availability; the risk lies mainly with confidentiality or integrity of process data.

No strong energy-sector-specific signals recognised; general OT/ICS relevance.

Recommended defensive measures

•Apply the latest firmware or software update and validate its integrity.
•Restrict network access to the affected device to a dedicated OT management segment.
•Implement network segmentation in line with zones and conduits (IEC 62443-3-2).
•Monitor for abnormal protocol traffic using an OT-aware detection system.

Industrial relevance score

40/ 100

• Mentioned in an official CISA ICS advisory, which confirms direct relevance to industrial control systems.

Classification is provisional; manual verification by an OT security analyst is recommended.

Classified by IACS Radar-analysepijplijn (geautomatiseerd) on 7 November 2026.

IEC 62443 mapping

IEC 62443-4-1FR3 · Systeemintegriteit

Automatic IACS Radar assessment based on the reported CWE weakness classification; not an official certification statement.

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