CVE-2021-28909
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 · uneditedBAB TECHNOLOGIE GmbH eibPort V3 prior version 3.9.1 allow unauthenticated attackers to access uncontrolled the login service at /webif/SecurityModule in a brute force attack. The password could be weak and default username is known as 'admin'. This is usable and part of an attack chain to gain SSH root access.
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 eibPort V3 web interface exposes the login endpoint at /webif/SecurityModule without any authentication requirement, allowing unauthenticated attackers to perform brute force attacks. Combined with the known default 'admin' username and potential weak passwords, this enables attackers to obtain valid credentials and chain this access to gain SSH root access on the device.
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< 3.9.1CVSS 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
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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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Identify eibPort V3 device on the networkDetermine if any network device is running the eibPort V3 web interface by accessing the device's IP address via HTTP/HTTPS in a web browser or using a network scanner to identify the service.Affected if The device is a Bab Technologie eibPort V3 unit with its web interface accessible on the network.
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Check installed firmware versionLog into the eibPort V3 web interface and navigate to the system information or firmware version page, typically found under Settings or System menu. Alternatively, check the login page footer or the startup page for the firmware version number.Affected if The installed firmware version is lower than 3.9.1, indicating the device is running a vulnerable version.
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Verify /webif/SecurityModule endpoint accessibilityAccess the URL http://[device-ip]/webif/SecurityModule directly in a web browser without providing any authentication credentials. Observe whether the login form or security module interface loads without requiring a login.Affected if The /webif/SecurityModule endpoint loads and displays a login form or security configuration interface without requiring prior authentication.
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Confirm default admin account is in useCheck if the default username 'admin' is still active on the device by attempting to log in with the username 'admin' and any known or default password, or by reviewing user account configuration if you have administrative access.Affected if The default 'admin' username exists and is active on the device, making brute force attacks feasible.
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Check SSH access configurationAttempt to connect to the device via SSH using the IP address (e.g., ssh root@[device-ip]) or access the device's SSH settings through the web interface if available. Verify whether root-level SSH access is permitted.Affected if SSH access to the device is enabled and root login is permitted, allowing attackers who obtain valid credentials to gain full system access.
A user is affected if they operate an eibPort V3 device with firmware version lower than 3.9.1 where the unauthenticated /webif/SecurityModule endpoint is accessible and the default admin account or weak SSH access is present.
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.
dbcve · scoped3.9.1
Upgrade to eibPort V3 version 3.9.1 or later which addresses this vulnerability. Additionally, disable root SSH access, enforce strong unique passwords, and implement network-level rate limiting on the web interface.
EibPort Firmware version 3.9.1
- 1. Obtain the EibPort Firmware version 3.9.1 from the official BAB TECHNOLOGIE GmbH vendor source
- 2. Access the EibPort device administrative interface
- 3. Navigate to the firmware update or system settings section
- 4. Upload and apply the firmware version 3.9.1
- 5. Verify the upgrade completed successfully and the device is operational
- 6. After upgrade, change the default 'admin' password to a strong, unique password
- 7. Confirm the /webif/SecurityModule endpoint now has appropriate authentication rate limiting in place
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-28909 — 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-2021-28909 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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