CVE intelligence and bounded remediation

CVE-2021-20708 — Nec Aterm Wf1200Cr Firmware security vulnerability

High CVSS 9

NEC Aterm devices (Aterm WF1200CR firmware Ver1.3.2 and earlier, Aterm WG1200CR firmware Ver1.3.3 and earlier, and Aterm WG2600HS firmware Ver1.5.1 and earlier) allow authenticated attackers to execute arbitrary OS commands by sending a specially crafted request to a specific URL.

Severity
High
CVSS
9 (2.0)
Published
2021-04-26
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-78

Affected products

  • nec / aterm_wf1200cr_firmware
  • nec / aterm_wg1200cr_firmware
  • nec / aterm_wg2600hs_firmware

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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