CVE-2021-27251

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR Nighthawk R7800. Authentication is not required to exploit this vulnerability The specific flaw exists within handling of firmware updates. The issue results from a fallback to a insecure protocol to deliver updates. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-12308.

Published: 2021-04-14 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-27251 is rated Moderate Risk (52.9/100): CVSS High severity, with low exploitation likelihood (EPSS 0.73%). Review affected assets and schedule 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-2021-27251

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 2026-06-15 0.29% 0.73% +0.44%
2 2025-09-05 0.22% 0.29% +0.08%
3 2025-03-30 — 0.22% —

Full EPSS history (12 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-27251

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-2021-27251

Affected software / configurations for CVE-2021-27251

Vendor Product Version Raw CPE
netgear br200_firmware < 5.10.0.5 cpe:2.3:o:netgear:br200_firmware:*:*:*:*:*:*:*:*
netgear br500_firmware < 5.10.0.5 cpe:2.3:o:netgear:br500_firmware:*:*:*:*:*:*:*:*
netgear d7800_firmware < 1.0.1.60 cpe:2.3:o:netgear:d7800_firmware:*:*:*:*:*:*:*:*
netgear ex6100v2_firmware < 1.0.1.98 cpe:2.3:o:netgear:ex6100v2_firmware:*:*:*:*:*:*:*:*
netgear ex6150_firmware < 1.0.1.98 cpe:2.3:o:netgear:ex6150_firmware:*:*:*:*:*:*:*:*
netgear ex6250_firmware < 1.0.0.134 cpe:2.3:o:netgear:ex6250_firmware:*:*:*:*:*:*:*:*
netgear ex6400_firmware < 1.0.2.158 cpe:2.3:o:netgear:ex6400_firmware:*:*:*:*:*:*:*:*
netgear ex6400v2_firmware < 1.0.0.134 cpe:2.3:o:netgear:ex6400v2_firmware:*:*:*:*:*:*:*:*
netgear ex6410_firmware < 1.0.0.134 cpe:2.3:o:netgear:ex6410_firmware:*:*:*:*:*:*:*:*
netgear ex6420_firmware < 1.0.0.134 cpe:2.3:o:netgear:ex6420_firmware:*:*:*:*:*:*:*:*
netgear ex7300_firmware < 1.0.2.158 cpe:2.3:o:netgear:ex7300_firmware:*:*:*:*:*:*:*:*
netgear ex7300v2_firmware < 1.0.0.134 cpe:2.3:o:netgear:ex7300v2_firmware:*:*:*:*:*:*:*:*
netgear ex7320_firmware < 1.0.0.134 cpe:2.3:o:netgear:ex7320_firmware:*:*:*:*:*:*:*:*
netgear ex7700_firmware < 1.0.0.216 cpe:2.3:o:netgear:ex7700_firmware:*:*:*:*:*:*:*:*
netgear ex8000_firmware < 1.0.1.232 cpe:2.3:o:netgear:ex8000_firmware:*:*:*:*:*:*:*:*
netgear lbr20_firmware < 2.6.3.50 cpe:2.3:o:netgear:lbr20_firmware:*:*:*:*:*:*:*:*
netgear r7800_firmware < 1.0.2.80 cpe:2.3:o:netgear:r7800_firmware:*:*:*:*:*:*:*:*
netgear r8900_firmware < 1.0.5.28 cpe:2.3:o:netgear:r8900_firmware:*:*:*:*:*:*:*:*
netgear r9000_firmware < 1.0.5.28 cpe:2.3:o:netgear:r9000_firmware:*:*:*:*:*:*:*:*
netgear rbk12_firmware < 2.7.2.104 cpe:2.3:o:netgear:rbk12_firmware:*:*:*:*:*:*:*:*
netgear rbk13_firmware < 2.7.2.104 cpe:2.3:o:netgear:rbk13_firmware:*:*:*:*:*:*:*:*
netgear rbk14_firmware < 2.7.2.104 cpe:2.3:o:netgear:rbk14_firmware:*:*:*:*:*:*:*:*
netgear rbk15_firmware < 2.7.2.104 cpe:2.3:o:netgear:rbk15_firmware:*:*:*:*:*:*:*:*
netgear rbk20_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbk20_firmware:*:*:*:*:*:*:*:*
netgear rbk23_firmware < 2.7.2.104 cpe:2.3:o:netgear:rbk23_firmware:*:*:*:*:*:*:*:*
netgear rbk40_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbk40_firmware:*:*:*:*:*:*:*:*
netgear rbk43_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbk43_firmware:*:*:*:*:*:*:*:*
netgear rbk43s_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbk43s_firmware:*:*:*:*:*:*:*:*
netgear rbk44_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbk44_firmware:*:*:*:*:*:*:*:*
netgear rbk50_firmware < 2.7.2.104 cpe:2.3:o:netgear:rbk50_firmware:*:*:*:*:*:*:*:*
netgear rbk53_firmware < 2.7.2.104 cpe:2.3:o:netgear:rbk53_firmware:*:*:*:*:*:*:*:*
netgear rbr10_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbr10_firmware:*:*:*:*:*:*:*:*
netgear rbr20_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbr20_firmware:*:*:*:*:*:*:*:*
netgear rbr40_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbr40_firmware:*:*:*:*:*:*:*:*
netgear rbr50_firmware < 2.7.2.104 cpe:2.3:o:netgear:rbr50_firmware:*:*:*:*:*:*:*:*
netgear rbs10_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbs10_firmware:*:*:*:*:*:*:*:*
netgear rbs20_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbs20_firmware:*:*:*:*:*:*:*:*
netgear rbs40_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbs40_firmware:*:*:*:*:*:*:*:*
netgear rbs50_firmware < 2.7.2.104 cpe:2.3:o:netgear:rbs50_firmware:*:*:*:*:*:*:*:*
netgear rbs50y_firmware < 2.6.2.104 cpe:2.3:o:netgear:rbs50y_firmware:*:*:*:*:*:*:*:*
netgear xr450_firmware < 2.3.2.114 cpe:2.3:o:netgear:xr450_firmware:*:*:*:*:*:*:*:*
netgear xr500_firmware < 2.3.2.114 cpe:2.3:o:netgear:xr500_firmware:*:*:*:*:*:*:*:*
netgear xr700_firmware < 1.0.1.38 cpe:2.3:o:netgear:xr700_firmware:*:*:*:*:*:*:*:*

References for CVE-2021-27251

cvelogic Threat Intelligence