CVE-2020-27866

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.

Published: 2021-02-12 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-27866 is rated High Risk (69.6/100): CVSS High severity, with high exploitation likelihood (EPSS 90.36%, 100th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2020-27866

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-10 90.84% 90.36% -0.48%
2 2026-03-04 90.26% 90.84% +0.58%
3 2026-03-01 — 90.26% —

Full EPSS history (37 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-27866

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.8 3.1 HIGH
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]
8.8 3.0 HIGH
CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:A)
Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]
8.3 2.0 HIGH
AV:A/AC:L/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:A)
Requires access to an adjacent network segment.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 6.5 10.0 [email protected]

Weakness enumeration for CVE-2020-27866

Affected software / configurations for CVE-2020-27866

Vendor Product Version Raw CPE
netgear ac2100_firmware < 1.2.0.76 cpe:2.3:o:netgear:ac2100_firmware:*:*:*:*:*:*:*:*
netgear ac2400_firmware < 1.2.0.76 cpe:2.3:o:netgear:ac2400_firmware:*:*:*:*:*:*:*:*
netgear ac2600_firmware < 1.2.0.76 cpe:2.3:o:netgear:ac2600_firmware:*:*:*:*:*:*:*:*
netgear r6700_firmware < 1.2.0.76 cpe:2.3:o:netgear:r6700_firmware:*:*:*:*:*:*:*:*
netgear r6800_firmware < 1.2.0.76 cpe:2.3:o:netgear:r6800_firmware:*:*:*:*:*:*:*:*
netgear r6900_firmware < 1.2.0.76 cpe:2.3:o:netgear:r6900_firmware:*:*:*:*:*:*:*:*
netgear r7200_firmware < 1.2.0.76 cpe:2.3:o:netgear:r7200_firmware:*:*:*:*:*:*:*:*
netgear r7350_firmware < 1.2.0.76 cpe:2.3:o:netgear:r7350_firmware:*:*:*:*:*:*:*:*
netgear r7400_firmware < 1.2.0.76 cpe:2.3:o:netgear:r7400_firmware:*:*:*:*:*:*:*:*
netgear r7450_firmware < 1.2.0.76 cpe:2.3:o:netgear:r7450_firmware:*:*:*:*:*:*:*:*
netgear r6220_firmware < 1.1.0.104 cpe:2.3:o:netgear:r6220_firmware:*:*:*:*:*:*:*:*
netgear r6230_firmware < 1.1.0.104 cpe:2.3:o:netgear:r6230_firmware:*:*:*:*:*:*:*:*
netgear r6260_firmware < 1.1.0.78 cpe:2.3:o:netgear:r6260_firmware:*:*:*:*:*:*:*:*
netgear r6330_firmware < 1.1.0.78 cpe:2.3:o:netgear:r6330_firmware:*:*:*:*:*:*:*:*
netgear r6350_firmware < 1.1.0.78 cpe:2.3:o:netgear:r6350_firmware:*:*:*:*:*:*:*:*
netgear r6850_firmware < 1.1.0.78 cpe:2.3:o:netgear:r6850_firmware:*:*:*:*:*:*:*:*
netgear r6120_firmware < 1.0.0.76 cpe:2.3:o:netgear:r6120_firmware:*:*:*:*:*:*:*:*
netgear r6020_firmware < 1.0.0.48 cpe:2.3:o:netgear:r6020_firmware:*:*:*:*:*:*:*:*
netgear r6080_firmware < 1.0.0.48 cpe:2.3:o:netgear:r6080_firmware:*:*:*:*:*:*:*:*

References for CVE-2020-27866

cvelogic Threat Intelligence