dbcve.org
ZldOperating system · Zyxel

CVE-2024-42058

HIGH · 7.5 CVSS v3.1 Published 2024-09-03
Fix available
A fix is available. Upgrade to 5.39 or later.
See remediation →
84/100
Remediation priority · High
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 null pointer dereference vulnerability in Zyxel ATP series firmware versions from V4.32 through V5.38, USG FLEX series firmware versions from V4.50 through V5.38, USG FLEX 50(W) series firmware versions from V5.20 through V5.38, and USG20(W)-VPN series firmware versions from V5.20 through V5.38 could allow an unauthenticated attacker to cause DoS conditions by sending crafted packets to a vulnerable device.

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

A null pointer dereference vulnerability in Zyxel ATP, USG FLEX, USG FLEX 50(W), and USG20(W)-VPN series firewall firmware allows an unauthenticated attacker to cause denial of service by sending crafted packets to the vulnerable device.

MitigationApply vendor-supplied firmware updates to address the null pointer dereference vulnerability; until patched, monitor for DoS indicators and consider network segmentation.

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
ZldOperating system
Affected:>= 4.32, < 5.39>= 4.50, < 5.39>= 4.20, < 5.39

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 the Zyxel firewall model
    Log into the device web interface or CLI and locate the model number in System > Status or equivalent. Look for ATP, USG FLEX, USG FLEX 50(W), or USG20(W)-VPN in the model name.
    Affected if Model is NOT one of these four series (ATP, USG FLEX, USG FLEX 50(W), USG20(W)-VPN)
  2. Check the installed firmware version
    In the device web interface, go to System > Maintenance > Firmware or use the CLI command 'show version' to display the current firmware version.
    Affected if Firmware version is 5.39 or higher (these are patched)
  3. Compare firmware version against affected ranges
    If firmware is below version 5.39, verify the exact version number against these ranges: >=4.32 and <5.39, OR >=4.50 and <5.39, OR >=4.20 and <5.39. Any version from 4.20 up to (but not including) 5.39 falls within the affected range.
    Affected if Firmware version falls within any of the affected ranges (4.20 to 5.38.x)
  4. Verify network accessibility of the firewall
    Confirm the firewall management interface or WAN interface is reachable from untrusted networks. Check if remote management is enabled and exposed to the internet using 'show ip http server' or 'show ip https server' in CLI, or via the web interface under System > WWW.
    Affected if The device management interface is exposed to the internet or untrusted networks (this is required for the unauthenticated attacker to send crafted packets)

You are affected if you have an ATP, USG FLEX, USG FLEX 50(W), or USG20(W)-VPN device running firmware version 4.20 through 5.38.x, and the device is reachable from networks where an unauthenticated attacker could send packets to it.

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.

dbcve · scoped
Upgrade available Upgrade to 5.39 or later
Fixed in 5.39
Interim mitigation

Apply vendor-supplied firmware updates to address the null pointer dereference vulnerability; until patched, monitor for DoS indicators and consider network segmentation.

Recommended fix High confidence

Firmware version 5.39 or later for ATP, USG FLEX, USG FLEX 50(W), and USG20(W)-VPN series

  1. 1. Identify the specific Zyxel device model (ATP series, USG FLEX series, USG FLEX 50W, or USG20W-VPN) in your environment
  2. 2. Access the device management interface or CLI
  3. 3. Backup the current device configuration
  4. 4. Download the V5.39 or later firmware from the official Zyxel support website (www.zyxel.com) for your specific device model
  5. 5. Upload and install the firmware version 5.39 or newer following Zyxel's standard firmware upgrade procedure
  6. 6. After upgrade, verify the device is operational and the vulnerability is remediated
Caveat Review Zyxel release notes for any configuration or feature changes between your current version and V5.39

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Zld Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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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-2024-42058 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
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data