CVE-2023-33009
Zyxel · published 2023-05-24
Source record Collected from the National Vulnerability Database (NVD)
CISA Known Exploited Vulnerabilities
CISA lists this CVE as known exploited (added 2023-06-05).
- CISA's name for it: Zyxel Multiple Firewalls Buffer Overflow Vulnerability
- CISA's 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.
- Known ransomware campaign use, per CISA: Unknown
Source: CISA KEV catalog (CC0 1.0).
Description
Description by Zyxel Corporation via the CVE Program.
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 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.
Status at the source
- NVD status: Analyzed
Affected products, as the source lists them
| Vendor | Product | Versions |
|---|---|---|
| Zyxel | ATP series firmware | 4.60 through 5.36 Patch 1: affected |
| Zyxel | USG FLEX series firmware | 4.60 through 5.36 Patch 1: affected |
| Zyxel | USG FLEX 50(W) firmware | 4.60 through 5.36 Patch 1: affected |
| Zyxel | USG20(W)-VPN firmware | 4.60 through 5.36 Patch 1: affected |
| Zyxel | VPN series firmware | 4.60 through 5.36 Patch 1: affected |
| Zyxel | ZyWALL/USG series firmware | 4.60 through 4.73 Patch 1: affected |
Products named in NVD's CPE match criteria (23)
cpe:2.3:o:zyxel:atp100_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:atp200_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:atp500_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:atp100w_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:atp700_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:atp800_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_flex_100_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_flex_50_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_flex_200_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_flex_500_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_flex_700_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_flex_100w_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_flex_50w_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_20w-vpn_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:vpn100_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:vpn50_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:vpn300_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:vpn1000_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg20-vpn_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_40_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_40w_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_60w_firmware:*:*:*:*:*:*:*:*cpe:2.3:o:zyxel:usg_60_firmware:*:*:*:*:*:*:*:*
DeSpy has not checked any unit, hardware revision or firmware. A product missing here is not a statement that it is unaffected.
Scores, as their sources published them
- CVSS 3.1: 9.8 CRITICAL — as published by Zyxel Corporation (Secondary)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 3.1: 9.8 CRITICAL — as published by NIST (Secondary)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - SSVC — CISA's assessment (SSVC 2.0.3, CISA Coordinator): Exploitation: active · Automatable: yes · Technical impact: total
DeSpy does not score records. These are the sources' own values.
Weaknesses
Sources
References the source lists
- https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls
- https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-33009
Source dates: published 2023-05-24, last changed 2026-06-17. DeSpy's copy of this version is dated 2026-09-28.
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