Security readout for executives and security teams
Plain-English summary
This flaw lets an unauthenticated remote person tell whether usernames are valid on affected MB connect line mymbCONNECT24 or mbCONNECT24 systems. That does not directly change data or take systems down, but it can materially improve phishing, password guessing, and account-targeting efforts.
Executive priority
Treat as a high-priority exposure reduction issue for affected deployments. It is not evidence of compromise by itself, but it weakens account privacy and can support broader credential attacks against remote-access users.
Technical view
CVE-2021-34575 is a CWE-203 observable discrepancy issue in mymbCONNECT24 and mbCONNECT24 versions <= 2.8.0. Network access with no privileges or user interaction can enumerate valid users by comparing server responses. CVSS 3.1 is 7.5, driven by high confidentiality impact only.
Likely exposure
Exposure applies to network-reachable mymbCONNECT24 or mbCONNECT24 deployments running version 2.8.0 or earlier. The provided sources do not identify affected CPEs, deployment defaults, or whether hosted and self-managed variants differ.
Exploitation context
The source bundle does not report active exploitation, and KEV status is false. The vulnerability is low-complexity and unauthenticated, so exposed login or user-checking surfaces should be treated as realistic reconnaissance targets.
Researcher notes
The public facts in the bundle are narrow: affected products, <= 2.8.0 version scope, CWE-203, CVSS vector, and response-based user enumeration. No exploit publication, patch version, or detailed endpoint behavior is provided here.
Mitigation direction
- Inventory mymbCONNECT24 and mbCONNECT24 instances and confirm product versions.
- Check MB connect line or VDE guidance for fixed versions or vendor mitigations.
- Reduce internet exposure for affected authentication interfaces where operationally possible.
- Strengthen account protections against follow-on password guessing or phishing.
- Monitor for repeated username validation attempts or unusual authentication failures.
Validation and detection
- Confirm whether any deployment runs version 2.8.0 or earlier.
- Review exposed routes that return different responses for valid and invalid users.
- Check logs for enumeration-like authentication or account lookup patterns.
- Verify vendor guidance has been applied after remediation.
- Document residual exposure if vendor fix details are unavailable.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-203: Information exposure and cloud metadata lookup
Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-34575 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://cert.vde.com/de-de/advisories/vde-2021-030CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Observable Discrepancy
Observable Discrepancy represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.