CVE-2021-34575
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn MB connect line mymbCONNECT24, mbCONNECT24 in versions <= 2.8.0 an unauthenticated user can enumerate valid users by checking what kind of response the server sends.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe mymbCONNECT24 and mbCONNECT24 web applications in versions 2.8.0 and below contain a user enumeration vulnerability. The authentication mechanism returns different HTTP responses (such as error messages or timing differences) when valid versus invalid usernames are submitted, allowing unauthenticated attackers to programmatically determine which user accounts exist in the system.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 2.8.0<= 2.8.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Confirm mbCONNECT24 or mymbCONNECT24 is runningAccess the web application URL (typically on ports 80, 443, or configured custom ports) and verify the application is responsiveAffected if The web interface is accessible and responds to HTTP requests
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Identify the installed versionCheck the login page, about section, or HTTP response headers for version information; consult system documentation or admin interface for version detailsAffected if The installed version is 2.8.0 or lower
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Test login response for known-valid usernameSubmit a login request with a likely-valid username (such as 'admin' or 'administrator') and record the HTTP response code, error message, and response timeAffected if The response indicates the username exists or provides specific feedback about the username
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Test login response for random-invalid usernameSubmit a login request with a clearly invalid username (such as 'nonexistentuser123') and record the HTTP response code, error message, and response timeAffected if The response differs from the valid username test in message content, error wording, or response timing
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Compare authentication responsesCompare the responses from steps 3 and 4 - look for differences in error messages, HTTP status codes, or response latency between valid and invalid usernamesAffected if The application returns different messages or timing for valid vs invalid usernames, allowing user enumeration
You are affected if mbCONNECT24 or mymbCONNECT24 version 2.8.0 or lower is running and the login page reveals different responses for valid versus invalid usernames, enabling an attacker to enumerate existing user accounts.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataImplement uniform server responses for both valid and invalid usernames during authentication to prevent enumeration. This may involve modifying the login logic to return identical error messages and timing regardless of whether the username exists.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-34575 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-34575 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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