Remote user enumeration in mymbCONNECT24, mbCONNECT24 <= 2.9.0

published 2021-10-27 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-21230

cvss: 7.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 1.0%; EPSS 1.0% chance of exploitation in 30 days, percentile 64%
public exploits: 0; none known

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.

Exploit prediction

1.04% chance of exploitation in the next 30 days, higher than 64% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD	3.1	7.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:P/I:N/A:N

Affected products

MB connect line mymbCONNECT24
MB connect line mbCONNECT24

Classification

Weakness

CWE-204 Observable Response Discrepancy
CWE-203 Observable Discrepancy

References

cert.vde.com /en/advisories/VDE-2021-037/
third-party-advisory

Sources

CVE List CVE-2021-34580
NVD CVE-2021-34580

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary