Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2023-33009 is a critical-severity Classic Buffer Overflow (CWE-120) vulnerability in Zyxel Atp100 Firmware. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique NTDS (T1003.003); ranked in the top 2% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
A buffer overflow vulnerability exists in the notification function of multiple Zyxel firewall product lines. Affected devices include ATP series, USG FLEX series, USG FLEX 50(W), USG20(W)-VPN, VPN series running firmware 4.60 through 5.36 Patch 1, and ZyWALL/USG series running 4.60 through 4.73 Patch 1. The flaw is tracked as CWE-120 and carries a CVSS 3.1 score of 9.8.
An unauthenticated attacker can send specially crafted network traffic to the affected notification function, triggering the overflow. Successful exploitation yields denial-of-service conditions and potential remote code execution on the device without requiring user interaction or credentials.
Zyxel has published a security advisory detailing the buffer overflow issues and directing customers to apply the fixed firmware versions listed in the advisory. The vulnerability also appears in CISA's Known Exploited Vulnerabilities catalog, confirming observed in-the-wild activity.
EPSS scores have remained modest, with a recorded peak of 0.0617 and a current value of 0.0558.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2023-37198
Vulnerability Data
A buffer overflow vulnerability in the notification function in Zyxel ATP series firmware versions 4.60 through 5.36 Patch 1, USG FLEX series firmware versions 4.60 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.60 through 5.36 Patch 1, USG20(W)-VPN…
more
firmware versions 4.60 through 5.36 Patch 1, VPN series firmware versions 4.60 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.60 through 4.73 Patch 1, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device.
- CWE(s)
- KEV Date Added
- 05 June 2023
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
—
V5.2.1
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Platform-independent managed code eliminates the need for unchecked native buffer copies that are the root cause of classic buffer overflows.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Vulnerability identification processes such as code review or scanning detect classic buffer overflows before exploitation.
Routine patching replaces vulnerable code containing unchecked buffer copies with corrected versions.
Secure development practices directly enforce bounds checking and input validation that prevent classic buffer overflows.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.