CVE intelligence and bounded remediation

CVE-2020-27866 — Netgear Ac2100 Firmware security vulnerability

High CVSS 8.8

This vulnerability allows network-adjacent attackers to bypass authentication on affected installations of NETGEAR R6020, R6080, R6120, R6220, R6260, R6700v2, R6800, R6900v2, R7450, JNR3210, WNR2020, Nighthawk AC2100, and Nighthawk AC2400 routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the mini_httpd service, which listens on TCP port 80 by default. The issue results from incorrect string matching logic when accessing protected pages. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of root. Was ZDI-CAN-11355.

Severity
High
CVSS
8.8 (3.1)
Published
2021-02-12
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-288, CWE-287

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

Authentication bypass and missing authentication

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

Check exposure

  • Map every affected endpoint and protocol path, including alternate ports, legacy routes, recovery flows, service accounts, and machine-to-machine access.
  • Confirm which deployments enable the affected authentication mode and whether the interface is reachable from untrusted networks.
  • Review session, token, credential, and proxy trust configuration without attempting account takeover.

Remediate safely

  • Apply the supported fix and centralize fail-closed authentication before protected request handling.
  • Remove default or embedded credentials, rotate affected secrets and sessions, and bind authentication decisions to the intended audience and channel.
  • Add negative tests for alternate routes, malformed or absent credentials, recovery flows, and proxy-derived identity.

Authoritative sources

Complete CVE record and remediation plan

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