Home/CVE/Zyxel Multiple Firewalls Buffer Overflow Vulnerability
CVE

CVE-2023-33009

Zyxel Multiple Firewalls Buffer Overflow Vulnerability

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.

CRITICAL · CVSS 9.8 ⚠ CISA KEV EPSS 0.05577
Act now
  • Listed on CISA KEV (known exploited in the wild)
  • SSVC exploitation status: active
  • EPSS percentile: top 10% of all CVEs by exploitation likelihood
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬢

Required Remediation

Apply updates per vendor instructions.

⬡

Weakness Classification

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
▤

Affected Products & Versions

40
zyxel atp100 firmware>= 4.60 and < 5.36
zyxel atp100 firmwareall versions
zyxel atp200 firmware>= 4.60 and < 5.36
zyxel atp200 firmwareall versions
zyxel atp500 firmware>= 4.60 and < 5.36
zyxel atp500 firmwareall versions
zyxel atp100w firmware>= 4.60 and < 5.36
zyxel atp100w firmwareall versions
▣

Scoring & Timeline

9.8
CRITICAL · CVSS v3.1 · security@zyxel.com.tw
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD24 May 2023 · 01:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
SSVC triage · cisa-vulnrichment
Exploitation
active
Automatable
yes
Technical impact
total
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

1
cisaKEV-CVE-2023-33009
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-33009US Government Resource
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