CVE-2023-22920Network attack vector

Unauthenticated device access via factory Telnet misconfiguration

Published Feb 21, 2023 · Updated Mar 12, 2025

Improper access control in Zyxel LTE3316-M604 V2.00(ABMP.6)C0 allows remote attackers to access the device through Telnet. A factory-default setting left in the firmware for testing exposes Telnet access, but Zyxel has not disclosed the specific setting or credential involved. No prior authentication or user interaction is required; the published material does not specify which commands or data become available after access.

CVSS severity9.8
Critical
EPSS probability0.84%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Zyxel LTE3316-M604 V2.00(ABMP.6)C0 allows remote attackers to access the device through Telnet. A factory-default setting left in the firmware for testing exposes Telnet access, but Zyxel has not disclosed the specific setting or credential involved. No prior authentication or user interaction is required; the published material does not specify which commands or data become available after access.

The record

CVE
CVE-2023-22920
Published
Feb 21, 2023
Updated
Mar 12, 2025
Vendor
Zyxel Networks
Product
LTE3316-M604
Classifications
CWE-284, T1133
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 21, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 12, 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.

  1. Affected versionversion=V2.00(ABMP.6)C0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Zyxel Networks · LTE3316-M604version=V2.00(ABMP.6)C0

Published CVSS scores

9.8Zyxel CorporationCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-284Improper Access Control
T1133External Remote Services

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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