CVE-2023-33009 — Zyxel Multiple Firewalls Buffer Overflow Vulnerability

CVE-2023-33009 (Zyxel Multiple Firewalls) is in the CISA Known Exploited Vulnerabilities catalog since 2023-06-05. Zyxel ATP, USG FLEX, USG FLEX 50(W), USG20(W)-VPN, VPN, and ZyWALL/USG firewalls contain a buffer overflow… See the required fix, due date and advisories.

Exploitation status

CVE-2023-33009 is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, added 2023-06-05. Zyxel ATP, USG FLEX, USG FLEX 50(W), USG20(W)-VPN, VPN, and ZyWALL/USG firewalls contain a buffer overflow vulnerability in the notification function that could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and remote code execution on an affected device.

Advisory facts

Vendor or project
Zyxel
Affected product
Multiple Firewalls
Added to CISA KEV
2023-06-05
US federal remediation due date
2023-06-26
Ransomware association
Unknown
EPSS score
—
Weakness (CWE)
CWE-120

Remediation: the required action

Apply updates per vendor instructions.

Wording published by CISA for this catalog entry. It is the baseline action, not a decision about your environment: whether this exposure matters for you depends on where the affected component runs, what it is exposed to and who owns it.

From advisory to a decision you can defend

A catalog entry tells you a vulnerability is being exploited somewhere. It does not tell you whether it matters in your estate, who owns the fix, or what evidence an auditor will ask for later. That is the work VulnTrek does: it takes findings from the tools you already run, decides which exposure actually matters, routes it to an owner, keeps remediation human-approved and retains the lineage as evidence.

Sourced from public upstream advisories (CISA KEV, ENISA EUVD, vendor PSIRTs) mirrored daily. Informational only — not a remediation decision, not legal advice, and the absence of a record is not evidence of safety.