CVE-2017-5159
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 · uneditedAn issue was discovered on Phoenix Contact mGuard devices that have been updated to Version 8.4.0. When updating an mGuard device to Version 8.4.0 via the update-upload facility, the update will succeed, but it will reset the password of the admin user to its default value.
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 confidenceWhen updating Phoenix Contact mGuard devices to Version 8.4.0 via the built-in update-upload facility, the firmware update completes successfully but inadvertently resets the admin user account password to its factory default value. This creates an authentication backdoor, allowing attackers with knowledge of the default credentials to gain administrative access to the affected 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= 8.4.0CVSS 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
- 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 the device modelLog into the device web interface or CLI and check the device information to confirm it is a Phoenix Contact mGuard device.Affected if The device is a Phoenix Contact mGuard model.
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Check the installed firmware versionNavigate to the device's system status or firmware information page in the web interface, or run the appropriate CLI command to display the firmware version.Affected if The firmware version is exactly 8.4.0.
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Determine how the firmware was updatedReview the device logs or update history to confirm whether the device was updated to 8.4.0 using the built-in update-upload facility rather than an alternate method.Affected if The device was updated to 8.4.0 via the built-in update-upload facility.
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Verify the admin password statusAttempt to log in with the known default admin credentials, or check the user management settings to determine whether the admin password has been changed from the factory default since the update.Affected if The admin password remains at the factory default value or can be accessed using the default credentials.
A user is affected if they have a Phoenix Contact mGuard device running firmware version 8.4.0 that was updated using the built-in update-upload facility, and the admin password has not been changed from its factory default since the update.
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 dataImmediately change the admin password on all mGuard devices that were updated to version 8.4.0, as the default credentials are publicly known. Consider avoiding the 8.4.0 update until a vendor patch is available, or contact Phoenix Contact for guidance on a secure update path.
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2017-5159 — 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-2017-5159 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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