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

CVE-2023-33010 is rated critical with a CVSS v3.1 base score of 9.8 and affects Zyxel Multiple Firewalls, along with 21 other products in NVD’s configuration data. Per its scoring, it can be exploited over the network, without authentication, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available. CISA added it to its Known Exploited Vulnerabilities catalog on 2023-06-05, which means exploitation in the wild has been observed.

Vulnerability description

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.

Severity breakdown

CVSS v3.1 9.8: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: None. No account or prior access is needed.
  • User interaction: None. No action from any user is needed.
  • Scope: Unchanged. Impact stays within the vulnerable component.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-120: Buffer Copy without Checking Size of Input

The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

Affected products

  • Zyxel Usg Flex 50w Firmware: from 4.25 before 5.36; 5.36; 5.36 patch1
  • Zyxel Usg 20w VPN Firmware: 5.36; 5.36 patch1
  • Zyxel Atp100 Firmware: from 4.32 before 5.36; 5.36; 5.36 patch1
  • Zyxel Atp200 Firmware: from 4.32 before 5.36; 5.36; 5.36 patch1
  • Zyxel Atp500 Firmware: from 4.32 before 5.36; 5.36; 5.36 patch1
  • Zyxel Atp100w Firmware: from 4.32 before 5.36; 5.36; 5.36 patch1
  • Zyxel Atp700 Firmware: from 4.32 before 5.36; 5.36; 5.36 patch1
  • Zyxel Atp800 Firmware: from 4.32 before 5.36; 5.36; 5.36 patch1
  • Zyxel Usg Flex 100 Firmware: from 4.50 before 5.36; 5.36; 5.36 patch1
  • Zyxel Usg Flex 50 Firmware: 5.36; 5.36 patch1
  • Zyxel Usg Flex 200 Firmware: from 4.50 before 5.36; 5.36; 5.36 patch1
  • Zyxel Usg Flex 500 Firmware: from 4.50 before 5.36; 5.36; 5.36 patch1
  • Zyxel Usg Flex 700 Firmware: from 4.50 before 5.36; 5.36; 5.36 patch1
  • Zyxel Usg Flex 100w Firmware: 5.36; 5.36 patch1
  • Zyxel Vpn100 Firmware: from 4.30 before 5.36; 5.36; 5.36 patch1

References