CVE-2023-33010: in the CISA KEV catalogue
Zyxel Multiple Firewalls Buffer Overflow Vulnerability. CISA added CVE-2023-33010 to the Known Exploited Vulnerabilities catalogue on 2023-06-05 with a default due date of 2023-06-26. Known ransomware campaign use: Unknown. Forensic triage flag: No.
Zyxel ATP, USG FLEX, USG FLEX 50(W), USG20(W)-VPN, VPN, and ZyWALL/USG firewalls contain a buffer overflow vulnerability in the ID processing function that could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and remote code execution on an affected device. (CISA description)
- Vendor / product
- Zyxel Multiple Firewalls
- CWE
- CWE-120
- CISA required action
- Apply updates per vendor instructions.
- EPSS
- 29%, percentile 98 (scored 2026-11-03)
EPSS puts about 29 in 100 odds (29%) on exploitation activity being observed in the next 30 days. Its score is higher than or equal to that of 98% of scored CVEs. This is a model estimate about exploitation anywhere, not about your environment.
Vendor and reference links (from CISA)
Your own deadline under CISA BOD 26-04 depends on exposure, automatability and technical impact: work it out with the BOD 26-04 calculator.
Frequently asked questions
Is CVE-2023-33010 in the CISA KEV catalogue?
Yes. CISA added CVE-2023-33010 (Zyxel Multiple Firewalls Buffer Overflow Vulnerability) to the Known Exploited Vulnerabilities catalogue on 2023-06-05. CISA's default due date for it is 2023-06-26.
Is CVE-2023-33010 used in ransomware attacks?
CISA marks known ransomware campaign use as Unknown for CVE-2023-33010. That means CISA lacks confirmation, not that ransomware groups do not use it.
What should I do about CVE-2023-33010?
CISA's required action: Apply updates per vendor instructions.
Sources
- CISA, Known Exploited Vulnerabilities Catalog (accessed 2026-11-03)
- FIRST, Exploit Prediction Scoring System (EPSS) (EPSS by FIRST; scores generated by Empirical Security)
- NVD record for CVE-2023-33010