CVE intelligence and bounded remediation

CVE-2020-27867 — Netgear Ac2100 Firmware security vulnerability

High CVSS 7.7

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR R6020, R6080, R6120, R6220, R6260, R6700v2, R6800, R6900v2, R7450, JNR3210, WNR2020, Nighthawk AC2100, and Nighthawk AC2400 routers. Although authentication is required to exploit this vulnerability, the existing authentication mechanism can be bypassed. The specific flaw exists within the mini_httpd service, which listens on TCP port 80 by default. When parsing the funjsq_access_token parameter, the process does not properly validate a user-supplied string before using it to execute a system call. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-11653.

Severity
High
CVSS
7.7 (2.0)
Published
2021-02-12
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-77

Affected products

  • netgear / ac2100_firmware
  • netgear / ac2400_firmware
  • netgear / ac2600_firmware
  • netgear / r6700_firmware
  • netgear / r6800_firmware
  • netgear / r6900_firmware

Showing 6 representative product identities from 19 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Command, code, expression, and template injection

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

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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