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Vulnerabilities

Vulnerability · CVE-2023-33010

Zyxel Multiple Firewalls Buffer Overflow Vulnerability

Published May 24, 2023 · catalog updated Jun 16, 2026 · Zyxel Multiple Firewalls

Patch now

CVE-2023-33010 is in the CISA known-exploited catalog, due Jun 26, 2023. Confirm Zyxel Multiple Firewalls against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Severity
Critical9.8
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
29.02%
Remediation
Remediation guidance
Affected products
cpe zyxel/atp100 firmware · cpe zyxel/atp100w firmware · cpe zyxel/atp200 firmware · cpe zyxel/atp500 firmware · cpe zyxel/atp700 firmware · cpe zyxel/atp800 firmware

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 4.25 through 5.36 Patch 1, VPN series firmware versions 4.30 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.25 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe zyxel/atp100 firmware5.36
  • cpe zyxel/atp100w firmwareversion unspecified
  • cpe zyxel/atp200 firmware5.36
  • cpe zyxel/atp500 firmware5.36
  • cpe zyxel/atp700 firmwareversion unspecified
  • cpe zyxel/atp800 firmwareversion unspecified
  • cpe zyxel/usg flex 100 firmwareversion unspecified
  • vendor Zyxel Multiple Firewallsversion unspecified

How to fix CVE-2023-33010

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2023-33010 is in the CISA known-exploited catalog, due Jun 26, 2023. Confirm Zyxel Multiple Firewalls against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with zyxel/atp100 firmware 5.36; zyxel/atp200 firmware 5.36; zyxel/atp500 firmware 5.36. Apply updates per vendor instructions.

What should an analyst verify?

CWE-120: Classic Buffer Overflow. EPSS 29.02%. The CISA KEV listing is the exploitation evidence. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 24, 2023 · Catalog

    Detected

    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 4.25 through 5.36 Patch 1, VPN series firmware versions 4.30 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.

  2. Jun 5, 2023 · CISA KEV

    Known exploited

    Apply updates per vendor instructions.

  3. Jun 26, 2023 · CISA KEV

    Remediation due

    Apply updates per vendor instructions.

  4. Jun 16, 2026 · Catalog

    Updated

    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 4.25 through 5.36 Patch 1, VPN series firmware versions 4.30 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.

Sources

  • CISA KEVConfirmed exploitationCVE-2023-33010

    Zyxel ATP, USG FLEX, USG FLEX 50(W), USG20(W)-VPN, VPN, and ZyWALL/USG firewalls contain a buffer overflow vulnerability in the ID processing function that could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and remote code execution on an affected device.

    cisa.gov
  • CVE.orgVulnerability recordCVE-2023-33010

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2023-33010

    30-day exploitation probability 29.0%

    first.org
  • NIST NVDVulnerability recordCVE-2023-33010

    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

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2023-33010

    Zyxel ATP, USG FLEX, USG FLEX 50(W), USG20(W)-VPN, VPN, and ZyWALL/USG firewalls contain a buffer overflow vulnerability in the ID processing function that could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and remote code execution on an affected

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.