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Fencer Intel
high 8.8

CVE-2021-27251 json

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR Nighthawk R7800.

published 5y ago modified 4mo ago also EUVD-2021-14016

cvss
8.8
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 57%
public exploits
0
none known

Summary

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.

Patch / fix

  • netgear br200_firmware 5.10.0.5
  • netgear br500_firmware 5.10.0.5
  • netgear d7800_firmware 1.0.1.60
  • netgear ex6100v2_firmware 1.0.1.98
  • netgear ex6150_firmware 1.0.1.98
  • netgear ex6250_firmware 1.0.0.134
  • netgear ex6400_firmware 1.0.2.158
  • netgear ex6400v2_firmware 1.0.0.134
  • netgear ex6410_firmware 1.0.0.134
  • netgear ex6420_firmware 1.0.0.134
  • netgear ex7300_firmware 1.0.2.158
  • netgear ex7300v2_firmware 1.0.0.134
  • netgear ex7320_firmware 1.0.0.134
  • netgear ex7700_firmware 1.0.0.216
  • netgear ex8000_firmware 1.0.1.232
  • netgear lbr20_firmware 2.6.3.50
  • netgear r7800_firmware 1.0.2.80
  • netgear r8900_firmware 1.0.5.28
  • netgear r9000_firmware 1.0.5.28
  • netgear rbk12_firmware 2.7.2.104

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Exploit prediction

0.81% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.0 8.8 CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 8.8 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 8.3 AV:A/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • NETGEAR R7800

Classification

Weakness
  • CWE-319 Cleartext Transmission of Sensitive Information

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.