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Actively exploited in the wild. This CVE is on the CISA Known Exploited Vulnerabilities list — treat remediation as urgent. Federal remediation due by 24 Dec 2024. Known ransomware use
ZldOperating system · Zyxel

CVE-2024-11667

CRITICAL · 9.8 CVSS v3.1 Published 2024-11-27
Fix available
A fix is available. Upgrade to after 5.38 or later.
See remediation →
100/100
Remediation priority · Urgent
In the wild Ransomware 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 directory traversal vulnerability in the web management interface of Zyxel ATP series firmware versions V5.00 through V5.38, USG FLEX series firmware versions V5.00 through V5.38, USG FLEX 50(W) series firmware versions V5.10 through V5.38, and USG20(W)-VPN series firmware versions V5.10 through V5.38 could allow an attacker to download or upload files via a crafted URL.

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 directory traversal vulnerability exists in the web management interface of Zyxel ATP, USG FLEX, USG FLEX 50(W), and USG20(W)-VPN series security gateways. Attackers can manipulate URLs using path traversal sequences (e.g., ../) to access files outside the intended web root directory, enabling unauthorized file downloads or potentially file uploads. The vulnerability affects firmware versions V5.00 through V5.38 across all affected product lines.

MitigationUpdate firmware to version V5.39 or later which contains the patch. If immediate updating is not feasible, restrict management interface access to trusted IP addresses only using firewall rules, and disable remote management capabilities if not required.

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:>= 5.00, <= 5.38>= 5.10, <= 5.38

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 the device model
    Log into the firewall web management interface and navigate to Status > System Information, or use CLI command 'show system-info' to confirm the exact model (ATP, USG FLEX, USG FLEX 50(W), or USG20(W)-VPN series)
    Affected if The device is not one of the listed affected series (ATP, USG FLEX, USG FLEX 50W, USG20W-VPN)
  2. Check the firmware version
    In the web interface, go to Maintenance > Firmware, or use CLI command 'show version' to determine the Zyxel Zld firmware version number
    Affected if The firmware version falls within Zld >= 5.00 to <= 5.38 OR >= 5.10 to <= 5.38 (this covers all affected versions in the range)
  3. Confirm web management interface is enabled
    In the web interface, go to Configuration > System > WWW and verify if the HTTPS or HTTP management service is enabled; in CLI, check 'show http server' or 'show webgui'
    Affected if The web management interface (HTTP/HTTPS) is enabled and accessible
  4. Assess network exposure of management interface
    Check firewall rules or ACLs under Configuration > Security Policy > Policy Control to see if the management interface (typically WAN or DMZ) is exposed to untrusted networks; verify no ACL restricts access to management IP to trusted sources only
    Affected if The web management interface is reachable from untrusted network segments (e.g., directly exposed to internet or DMZ without IP restrictions)

A user is affected if they run an ATP, USG FLEX, USG FLEX 50(W), or USG20(W)-VPN device with Zld firmware between versions 5.00-5.38 (or 5.10-5.38) AND have the web management interface enabled and accessible from untrusted networks.

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 a release after 5.38
Interim mitigation

Update firmware to version V5.39 or later which contains the patch. If immediate updating is not feasible, restrict management interface access to trusted IP addresses only using firewall rules, and disable remote management capabilities if not required.

Recommended fix Moderate confidence

V5.39 or later (firmware version greater than V5.38)

  1. Identify the specific Zyxel device model (ATP, USG FLEX, USG FLEX 50W, or USG20(W)-VPN) from the affected product list
  2. Locate the firmware download section on support.zyxel.com for your specific device model
  3. Download the latest available firmware version. Based on the affected range (V5.00-V5.38), look for firmware versions beyond V5.38 (such as V5.39 or later)
  4. Follow the standard Zyxel firmware upgrade procedure: backup the current configuration, upload the new firmware via the web management interface or CLI, and restore the configuration
  5. After upgrade, verify the firmware version matches the patched release
Caveat Review Zyxel release notes for any configuration or feature changes between your current version and the target version

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

Fix this in Zld Exploited in the wild — priority engagement
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing3.0 h
  • Review / QA2.0 h
10.0 hours of engineering $1,750
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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-2024-11667 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