SARA / Free Tools / CVE / CVE-2023-33010

CVE-2023-33010 — Zyxel Multiple Firewalls Buffer Overflow Vulnerability

A buffer overflow vulnerability in the ID processing function in Zyxel ATP series firmware versions 4.32 through 5.36 Patch 1, USG FLEX series firmware versions 4.50 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.25 through 5.36 Patch 1, USG20(W)-VPN firmware versions 4

CVSS

9.8 CRITICAL

EPSS

5.85% (top 9.50%)

CWE

CWE-120

Published

2023-05-24T00:00:00.000Z

Last modified

2025-10-21T23:05:47.497Z

CVSS vector

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

CISA KEV — Actively Exploited

Added to KEV

2023-06-05

BOD 22-01 due

2023-06-26

Ransomware use

Unknown

View KEV detail

CVE-2023-33010 on CISA KEV →

01What is this vulnerability?

02Affected products

Vendor	Product	Versions
Zyxel	ATP series firmware	4.32 through 5.36 Patch 1
Zyxel	USG FLEX series firmware	4.50 through 5.36 Patch 1
Zyxel	USG FLEX 50(W) firmware	4.25 through 5.36 Patch 1
Zyxel	USG20(W)	VPN firmware — 4.25 through 5.36 Patch 1
Zyxel	VPN series firmware	4.30 through 5.36 Patch 1
Zyxel	ZyWALL/USG series firmware	4.25 through 4.73 Patch 1

03Active exploitation status

Yes — actively exploited. Added to the CISA KEV catalog on 2023-06-05. Ransomware use: Unknown.

04Recommended remediation

Patch to a fixed version listed in the vendor advisory (see references below).
Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Open the Sigma generator with a pre-filled prompt for this CVE to draft a starting detection in your stack of choice:

Open in Sigma generator →

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

Published: 2023-05-24T00:00:00.000Z
Last modified: 2025-10-21T23:05:47.497Z
Added to CISA KEV: 2023-06-05
BOD 22-01 due: 2023-06-26

09References

www.zyxel.com — https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advis…

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