CVE intelligence and bounded remediation

CVE-2023-6764 — Zyxel Atp100 Firmware security vulnerability

High CVSS 8.1

A format string vulnerability in a function of the IPSec VPN feature in Zyxel ATP series firmware versions from 4.32 through 5.37 Patch 1, USG FLEX series firmware versions from 4.50 through 5.37 Patch 1, USG FLEX 50(W) series firmware versions from 4.16 through 5.37 Patch 1, and USG20(W)-VPN series firmware versions from 4.16 through 5.37 Patch 1 could allow an attacker to achieve unauthorized remote code execution by sending a sequence of specially crafted payloads containing an invalid pointer; however, such an attack would require detailed knowledge of an affected device’s memory layout and configuration.

Severity
High
CVSS
8.1 (3.1)
Published
2024-02-20
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-134

Affected products

  • zyxel / atp100_firmware
  • zyxel / atp100_firmware / 5.37
  • zyxel / atp100w_firmware
  • zyxel / atp100w_firmware / 5.37
  • zyxel / atp200_firmware
  • zyxel / atp200_firmware / 5.37

Showing 6 representative product identities from 63 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Command, code, expression, and template injection

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Check exposure

  • Trace untrusted values to process execution, interpreters, evaluators, template engines, dynamic imports, and administrative scripting features.
  • Determine whether the affected path is reachable across each trust boundary and which service account or host privilege it inherits.
  • Review configuration for optional execution features, unsafe compatibility modes, and shell invocation.

Remediate safely

  • Replace string-built commands or evaluated code with fixed operations and structured argument APIs that do not invoke a shell.
  • Use strict allowlists for operation identifiers and reject unexpected input before it reaches any interpreter.
  • Update the affected component and add inert regression tests covering metacharacters, encoding variants, and alternate request paths.

Authoritative sources

Complete CVE record and remediation plan

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