CVE Intelligence
CISA KEV Critical File handling

CVE-2024-11667 — Zyxel Multiple Firewalls Path Traversal Vulnerability

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.

Published Nov 27, 2024 · Updated Oct 13, 2026 · Sources: CISA Known Exploited Vulnerabilities, NIST National Vulnerability Database, GitHub Security Advisories, CVE Program (cve.org) e CISA ADP · CNA: Zyxel

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

CISA KEV · Dec 3, 2024 R used by ransomware (CISA)
How the score was calculated
  • Confirmed exploitation (CISA KEV)+35
  • Used in ransomware campaigns (CISA)+10
  • EPSS 2.9% (30-day exploitation probability)+13
  • Technical severity (critical)+10
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Confirmed
CISA KEV, listed Dec 3, 2024
EPSS FIRST
2.93%
ahead of 87% of scored CVEs · Oct 15, 2026
Affects
Zyxel
ATP series firmware and 4 more
CVSS base
9.8
Critical · 4 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
Active
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

CISA required action CISA

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

US federal deadline: Dec 24, 2024 — passed 661 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Zyxel ATP series firmware, Zyxel USG FLEX 50(W) series firmware, Zyxel USG FLEX series firmware…).
  2. Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
  3. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  4. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  5. Search available logs for exploit probes matching the vulnerability class (file handling), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Zyxel ATP series firmware version versions V5.00 through V5.38 Vulnerable CVE Program (cve.org) e CISA ADP
Zyxel USG FLEX 50(W) series firmware version versions V5.10 through V5.38 Vulnerable CVE Program (cve.org) e CISA ADP
Zyxel USG FLEX series firmware version versions V5.00 through V5.38 Vulnerable CVE Program (cve.org) e CISA ADP
Zyxel USG20(W)-VPN series firmware version versions V5.10 through V5.38 Vulnerable CVE Program (cve.org) e CISA ADP
Zyxel Zld ≥ 5.00 and ≤ 5.38≥ 5.10 and ≤ 5.38 Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
9.8 CVSS 3.1 Critical 3.9 5.9 nvd@nist.gov via NIST National Vulnerability Database
7.5 CVSS 3.1 High 3.9 3.6 security@zyxel.com.tw via NIST National Vulnerability Database
7.5 CVSS 3.1 High — — GitHub, Inc. via GitHub Security Advisories
7.5 CVSS 3.1 High — — Zyxel via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 9.8 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-22 · Path Traversal

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

Listed
Dec 3, 2024
Federal deadline
Dec 24, 2024
passed 661 day(s) ago
Ransomware use
Known

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 2.93%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Monitor file creation in web directories and paths with traversal sequences (../).
  • Hunt retroactively in logs from before Dec 3, 2024 (KEV listing): exploitation may have started earlier.
web/proxy/WAF logsnetwork IDS/IPSfile integrity (FIM)endpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · zyxel/atp series firmware, zyxel/usg flex series firmware, zyxel/usg flex 50(w) series firmware, zyxel/usg20(w)-vpn seri
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • Affected products added · zyxel/zld
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVSS changed · 9.8
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 13, 2026 · NIST National Vulnerability Database
  • Added to CISA KEV (detected)
    Oct 13, 2026 · CISA Known Exploited Vulnerabilities
  • Record created in this database
    Oct 13, 2026 · CISA Known Exploited Vulnerabilities
  • 2024
  • Added to CISA KEV catalog
    Dec 2, 2024 · CISA
  • CVE published
    Nov 27, 2024 · Zyxel

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 13, 2026 – Oct 13, 2026
  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

5 on the record

Elsewhere on this site

Zyxel
every CVE for this vendor
2024-12
what else CISA listed that month
File handling
same class
CWE-22
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-14818 Path Traversal in Zyxel ATP series firmware Aug 4, 2026
  • CVE-2025-11730 OS Command Injection in Zyxel ATP series firmware Feb 4, 2026
  • CVE-2025-9133 Missing Authorization in Zyxel Zld Oct 21, 2025
  • CVE-2025-8078 OS Command Injection in Zyxel Zld Oct 21, 2025
  • CVE-2023-33009 Zyxel Multiple Firewalls Buffer Overflow Vulnerability KEV May 24, 2023
  • CVE-2023-33010 Zyxel Multiple Firewalls Buffer Overflow Vulnerability KEV May 24, 2023

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2024-11667 is "Zyxel Multiple Firewalls Path Traversal Vulnerability", rated Critical. It affects ATP series firmware (Zyxel); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 9.8 describes technical severity. EPSS 2.93% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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