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Vulnerability record · CVE-2020-27866 · published 12 February 2021

CVE-2020-27866: Netgear ac2100 firmware authentication bypass via alternate path vulnerability

Netgear · Ac2100 Firmware

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.

8.8 CVSS 3.1 High EPSS 8.7% · top 5.1% CWE-288 · Authentication bypass via alternate pathCWE-287 · Improper authentication
8.8CVSS 3.1 base score, v2 8.3
8.7%EPSS exploitation probability, 30 days
NoNot in CISA KEV
19Affected product versions listed by NVD
4References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

19 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://kb.netgear.com/000062641/Security-Advisory-for-Password-Recovery-Vulnerabilities-on-Some-Routers Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-20-1451/ Third Party AdvisoryVDB Entry
https://kb.netgear.com/000062641/Security-Advisory-for-Password-Recovery-Vulnerabilities-on-Some-Routers Vendor Advisory
https://www.zerodayinitiative.com/advisories/ZDI-20-1451/ Third Party AdvisoryVDB Entry

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2021-45637Netgear r6260 firmware out-of-bounds write vulnerabilityCertain NETGEAR devices are affected by a stack-based buffer overflow by an unauthenticated attacker. This affects R6260 before 1.1.0.76, R6800 befor…EPSS 1.2%9.8CVE-2021-45644Netgear ac2100 firmware vulnerabilityCertain NETGEAR devices are affected by incorrect configuration of security settings. This affects AC2100 before 1.2.0.88, AC2400 before 1.2.0.88, AC…EPSS 1.1%9.8CVE-2021-45511Netgear ac2100 firmware vulnerabilityCertain NETGEAR devices are affected by authentication bypass. This affects AC2100 before 2021-08-27, AC2400 before 2021-08-27, AC2600 before 2021-08…EPSS 18%9.8CVE-2021-45501Netgear ac2400 firmware vulnerabilityCertain NETGEAR devices are affected by authentication bypass. This affects AC2400 before 1.1.0.84, AC2600 before 1.1.0.84, D7000 before 1.0.1.82, R6…EPSS 1.9%9.8CVE-2021-38516Netgear d6220 firmware vulnerabilityCertain NETGEAR devices are affected by lack of access control at the function level. This affects D6220 before 1.0.0.48, D6400 before 1.0.0.82, D700…EPSS 1.3%9.8CVE-2020-35795Netgear ac2100 firmware classic buffer overflow vulnerabilityCertain NETGEAR devices are affected by a buffer overflow by an unauthenticated attacker. This affects AC2100 before 1.2.0.72, AC2400 before 1.2.0.72…EPSS 1.2%9.8CVE-2020-35799Netgear d3600 firmware out-of-bounds write vulnerabilityCertain NETGEAR devices are affected by a stack-based buffer overflow by an unauthenticated attacker. This affects D3600 before 1.0.0.76, D6000 befor…EPSS 1.2%9.8CVE-2020-26927Netgear ac2100 firmware vulnerabilityCertain NETGEAR devices are affected by authentication bypass. This affects D6200 before 1.1.00.40, D7000 before 1.0.1.78, R6020 before 1.0.0.42, R60…EPSS 1.1%

Source: NIST National Vulnerability Database (record CVE-2020-27866), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.