Lte3202 M437 FirmwareOperating system · Zyxel

CVE-2023-22920

CRITICAL · 9.8 CVSS v3.1 Published 2023-02-21
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
A security misconfiguration vulnerability exists in the Zyxel LTE3316-M604 firmware version V2.00(ABMP.6)C0 due to a factory default misconfiguration intended for testing purposes. A remote attacker could leverage this vulnerability to access an affected device using Telnet.

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 confidence

The Zyxel LTE3316-M604 firmware V2.00(ABMP.6)C0 contains a factory default misconfiguration that enables remote Telnet access. This was left intentionally for testing but was never disabled before production release, allowing unauthenticated remote attackers to connect to the device over Telnet and potentially execute commands or extract sensitive information.

MitigationApply any available firmware update from Zyxel that removes the testing Telnet access; if no update exists, disable Telnet via device administration interface and ensure the device is not directly exposed to the internet.

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
Lte3202 M437 FirmwareOperating system
Affected:= 1.00\(abwf.1\)c0
Lte3316 M604 FirmwareOperating system
Affected:= 2.00\(abmp.6\)c0

CVSS 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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify device model
    Locate the device label or access the admin interface to confirm the model is LTE3316-M604 or LTE3202-M437
    Affected if Device is either LTE3316-M604 or LTE3202-M437
  2. Check firmware version
    Access the device administration interface (typically via web GUI at 192.168.1.1 or similar) and navigate to Status or System Info to view the firmware version. Compare against affected versions: LTE3316-M604 firmware = 2.00(ABMP.6)C0, LTE3202-M437 firmware = 1.00(abwf.1)c0
    Affected if Firmware version matches exactly 2.00(ABMP.6)C0 for LTE3316-M604 or 1.00(abwf.1)c0 for LTE3202-M437
  3. Verify Telnet service status
    From a computer on the same network, attempt to connect to the device using Telnet on port 23 (e.g., run 'telnet <device_ip>' in command prompt). If connection succeeds, Telnet is enabled
    Affected if Telnet connection succeeds and provides device access without authentication
  4. Check if Telnet allows remote access
    Attempt Telnet connection from an external network (outside the local LAN) or check the device firewall/security settings to determine if remote Telnet connections from WAN are permitted
    Affected if Telnet is accessible from WAN/external networks

The device is affected if it is a Zyxel LTE3316-M604 or LTE3202-M437 with the specific vulnerable firmware version AND Telnet service is enabled and accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply any available firmware update from Zyxel that removes the testing Telnet access; if no update exists, disable Telnet via device administration interface and ensure the device is not directly exposed to the internet.

Fix this in Lte3202 M437 Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,060
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-22920 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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