Root shell access via undocumented UART port
Published Dec 9, 2025 · Updated Dec 9, 2025
Missing UART protection in Phoenix Contact FL SWITCH/NAT 2xxx firmware before 3.50 allows physically proximate attackers to gain root access. An undocumented UART port on the device PCB exposes a login shell and accepts root credentials obtainable through the separately tracked weak-password condition. Physical access to the appliance and working root credentials are required, after which the attacker receives full shell control.
Summary
What happened
Missing UART protection in Phoenix Contact FL SWITCH/NAT 2xxx firmware before 3.50 allows physically proximate attackers to gain root access. An undocumented UART port on the device PCB exposes a login shell and accepts root credentials obtainable through the separately tracked weak-password condition. Physical access to the appliance and working root credentials are required, after which the attacker receives full shell control.
The record
- CVE
- CVE-2025-41697
- Published
- Dec 9, 2025
- Updated
- Dec 9, 2025
- Vendor
- Phoenix Contact
- Product
- FL SWITCH 2204-2TC-2SFX
- Classifications
- CWE-1299, T1059, T1200
- Attack vector
- physical
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 9, 2025CVE publishedPublication date reported by the CVE source.
- Dec 9, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0.0.0 <3.50
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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