CVE-2025-41697
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 attacker can use an undocumented UART port on the PCB as a side-channel to get root access e.g. with the credentials obtained from CVE-2025-41692.
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 · moderate confidenceThis is a physical hardware vulnerability where an undocumented UART (Universal Asynchronous Receiver/Transmitter) serial port on the device PCB can be exploited by an attacker with physical access. The attacker can use this side-channel to bypass authentication and obtain root access to the system, potentially in conjunction with credentials from related vulnerabilities.
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< 3.50< 3.50< 3.50< 3.50< 3.50< 3.50< 3.50< 3.50CVSS 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
- Physical
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:P/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 modelLocate the device label or use the device's web interface, CLI, or management console to identify the exact model number (e.g., FL Switch 2708 PN, FL Switch 2608, FL Switch 2516, or FL Switch 2514 2sfp)Affected if The device is a Phoenix Contact FL Switch 2514, 2516, 2608, or 2708 series model (PN or non-PN variants)
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Check the firmware versionAccess the device's web interface, CLI, or management console and navigate to the system information or firmware version section. Compare the installed firmware version against the affected range.Affected if The firmware version is less than 3.50 (e.g., 3.49.x, 3.40.x, etc.)
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Inspect the PCB for undocumented UART portsWith the device powered off and following proper ESD precautions, remove the chassis cover and visually inspect the PCB for any unlabeled, unpopulated, or exposed serial header pins that are not documented in the product manual.Affected if An undocumented UART port (unlabeled serial header, unpopulated pins, or debug interface not mentioned in documentation) is present on the PCB and accessible
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Verify console authentication statusIf an undocumented UART is found, attempt to connect to it using a serial terminal (9600 baud, 8N1) and observe whether the device grants shell access without requiring authentication or credentials.Affected if The undocumented UART provides unauthenticated console or root access
A defender is affected if they own a Phoenix Contact FL Switch 2514/2516/2608/2708 series device running firmware below version 3.50 that has an undocumented UART port on the PCB which provides unauthenticated access.
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 · scoped3.50
Disable or remove the undocumented UART port from the PCB production design, or implement strong authentication/console locking on any debug interfaces; physical security measures (tamper-evident seals, enclosed chassis) should also be considered to prevent unauthorized physical access.
Firmware version 3.50 or later for FL Switch 2708 PN, FL Switch 2708, FL Switch 2608 PN, FL Switch 2608, FL Switch 2516 PN, FL Switch 2516, FL Switch 2514 2sfp PN, FL Switch 2514 2sfp
- 1. Identify the specific FL Switch model (e.g., FL Switch 2708 PN, FL Switch 2608, etc.) currently deployed
- 2. Access the device management interface or console
- 3. Check the current firmware version to confirm it is below 3.50
- 4. Download the firmware version 3.50 or later from the manufacturer's official support website (certvde.com or vendor's website)
- 5. Follow the vendor's documented firmware upgrade procedure to apply version 3.50 or later
- 6. After upgrade, verify the new firmware version is correctly installed
- 7. Consider physical security controls to limit access to PCB debug ports as an additional defense-in-depth measure
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA3.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-41697 — 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-2025-41697 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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