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CVE-2023-33009

CISA KEV

Published June 5, 2023 · Updated April 3, 2026

high
Official Description+

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.

Affected Products

VendorProduct
ZyxelMultiple Firewalls

Patch Status

Patch by 2023-06-26

Recommended Actions

  1. Check if your systems use any of the affected products listed above.
  2. Apply vendor patches immediately if available.
  3. This vulnerability is in CISA's Known Exploited Vulnerabilities catalog — prioritize remediation.
  4. Monitor vendor advisories for updates and additional mitigations.
  5. Review logs for indicators of compromise related to CVE-2023-33009.