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CVE-2023-33009

82
FAUCET Score

CVE-2023-33009 is a critical buffer overflow vulnerability in the notification function of various Zyxel ATP, USG FLEX, VPN, and ZyWALL/USG series firmware versions. This flaw allows an unauthenticated attacker to cause denial-of-service (DoS) and potentially achieve remote code execution on affected devices. With a CVSS score of 9.8 (CRITICAL), the vulnerability is easily exploitable over the network without user interaction, leading to complete compromise of confidentiality, integrity, and availability. This CVE is actively exploited in the wild, as confirmed by its presence in the KEV catalog, and has garnered significant community attention and media coverage, despite a lack of public exploit intelligence tools.

Impacted Technologies

VendorProductVersion(s)CPE
>= 4.60, < 5.36CPE matchmatch criteria
cpe:2.3:o:zyxel:atp100_firmware:*:*:*:*:*:*:*:*
5.36CPE matchmatch criteria
cpe:2.3:o:zyxel:atp100_firmware:5.36:-:*:*:*:*:*:*
5.36CPE matchmatch criteria
cpe:2.3:o:zyxel:atp100_firmware:5.36:patch1:*:*:*:*:*:*
>= 4.60, < 5.36CPE matchmatch criteria
cpe:2.3:o:zyxel:atp200_firmware:*:*:*:*:*:*:*:*
5.36CPE matchmatch criteria
cpe:2.3:o:zyxel:atp200_firmware:5.36:-:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
28.14%
Probability of exploitation in next 30 days
EPSS Percentile
97.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
Added to KEV · Jun 5, 2023
This CVE's current EPSS score of 0.2814 is in the 95th percentile among its peer group of 36,833 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

cisa.gov / known-exploited-vulnerabilities-catalog
US Government Resource
zyxel.com / global/en/support/security-advisories/zyxel-security-advisory-for-multiple-buffer-overflow-vulnerabilities-of-firewalls
Vendor Advisory