CVE-2023-33009 kev in the critical feed json
A buffer overflow vulnerability in the notification function in Zyxel ATP series firmware versions 4.60 through 5.36 Patch 1, USG FLEX seri…
published 2023-05-24 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-37198
- cvss
- 9.8
- version 3.1, CNA
- cisa kev
- Exploited
- added 2023-06-05
- epss
- 28.1%
- EPSS 28.1% chance of exploitation in 30 days, percentile 98%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
cisa required action Apply updates per vendor instructions.
- zyxel atp100_firmware 5.36
- zyxel atp200_firmware 5.36
- zyxel atp500_firmware 5.36
- zyxel atp100w_firmware 5.36
- zyxel atp700_firmware 5.36
- zyxel atp800_firmware 5.36
- zyxel usg_flex_100_firmware 5.36
- zyxel usg_flex_50_firmware 5.36
- zyxel usg_flex_200_firmware 5.36
- zyxel usg_flex_500_firmware 5.36
- zyxel usg_flex_700_firmware 5.36
- zyxel usg_flex_100w_firmware 5.36
- zyxel usg_flex_50w_firmware 5.36
- zyxel usg_20w-vpn_firmware 5.36
- zyxel vpn100_firmware 5.36
- zyxel vpn50_firmware 5.36
- zyxel vpn300_firmware 5.36
- zyxel vpn1000_firmware 5.36
- zyxel usg20-vpn_firmware 5.36
- zyxel usg_40_firmware 4.73
Timeline
- Published
- Added to CISA KEV
- CISA patch deadline
- CISA SSVC: exploitation active
Known exploited
- Added
- 3 y ago
- Patch by
- 2023-06-26 (3 y ago)
- Ransomware
- Not known
- Required action
- Apply updates per vendor instructions.
- Vendor, product
- Zyxel, Multiple Firewalls
- CISA name
- Zyxel Multiple Firewalls Buffer Overflow Vulnerability
CISA SSVC
- Exploitation
- Active, exploited in the wild
- Automatable
- yes
- Technical impact
- total
- Assessed
- 21 mo ago
Exploit prediction
28.14% chance of exploitation in the next 30 days, higher than 98% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
Affected products
- Zyxel ATP series firmware
- Zyxel USG FLEX series firmware
- Zyxel USG FLEX 50(W) firmware
- Zyxel USG20(W)-VPN firmware
- Zyxel VPN series firmware
- Zyxel ZyWALL/USG series firmware
Classification
- Weakness
-
- CWE-120 Buffer Copy without Checking Size of Input
References
-
zyxel.com
/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of
vendor-advisory
-
cisa.gov
/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-33009
government-resource, us-government-resource
Sources
- CVE List CVE-2023-33009
- NVD CVE-2023-33009
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.