How severe is CVE-2020-27866?

CVE-2020-27866 has a CVSS score of 8.8/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2020-27866?

Affected package information for CVE-2020-27866 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2020-27866?

No fixed version has been published for CVE-2020-27866 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2020-27866 actively exploited in the wild?

No public exploit code has been indexed for CVE-2020-27866 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2020-27866?

CVE-2020-27866 has an EPSS (Exploit Prediction Scoring System) score of 90.4%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

What type of vulnerability is CVE-2020-27866?

CVE-2020-27866 is classified as CWE-288 (CWE-288), Improper Authentication (CWE-287). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2020-27866?

CVE-2020-27866 affects netgear ac2100 firmware; netgear ac2400 firmware; netgear ac2600 firmware; netgear r6020 firmware, and 15 more product(s). Check the affected-products list on this page against your deployed version to confirm exposure.

Is there exploit tooling available for CVE-2020-27866?

A Nuclei detection template exists for CVE-2020-27866, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2020-27866 published, and has it been updated?

CVE-2020-27866 was published on February 12, 2021 and was last updated on November 21, 2024. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2020-27866: Ac2100 Firmware CWE-288 (High 8.8)

EPSS Exploitation Probability

via FIRST.org ↗

90.4%probability of exploitation in next 30 days

Very High Risk100th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

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.

Affected Products

19 products · 19 configurations

OS

ac2100 firmwarenetgear

< 1.2.0.76

range

OS

ac2400 firmwarenetgear

< 1.2.0.76

range

OS

ac2600 firmwarenetgear

< 1.2.0.76

range

OS

r6020 firmwarenetgear

< 1.0.0.48

range

OS

r6080 firmwarenetgear

< 1.0.0.48

range

OS

r6120 firmwarenetgear

< 1.0.0.76

range

Frequently Asked Questions

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

O3 Security · Impact-Aware SCA

Is CVE-2020-27866 in your stack?

O3 detects CVE-2020-27866 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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