CVE-2021-34991

Severity: high (CVSS 8.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 5.7% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-11-15 · updated 2026-06-17
Weakness: CWE-121

Description

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of NETGEAR R6400v2 1.0.4.106_10.0.80 routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the UPnP service, which listens on TCP port 5000 by default. When parsing the uuid request header, the process does not properly validate the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of root. Was ZDI-CAN-14110.

Affected products

NETGEAR Cax80 Firmware: before 2.1.3.5 — fixed in 2.1.3.5
NETGEAR D6220 Firmware: before 1.0.0.76 — fixed in 1.0.0.76
Netgear D6400: before 1.0.0.108 — fixed in 1.0.0.108
NETGEAR D7000V2 Firmware: before 1.0.0.76 — fixed in 1.0.0.76
NETGEAR Dc112A Firmware: before 1.0.0.62 — fixed in 1.0.0.62
NETGEAR Dgn2200V4 Firmware: before 1.0.0.126 — fixed in 1.0.0.126
NETGEAR EX3700: before 1.0.0.94 — fixed in 1.0.0.94
NETGEAR Ex3800 Firmware: before 1.0.0.94 — fixed in 1.0.0.94
NETGEAR EX6120: before 1.0.0.66 — fixed in 1.0.0.66
NETGEAR Ex6130 Firmware: before 1.0.0.66 — fixed in 1.0.0.66
NETGEAR R6400 Firmware: before 1.0.1.76 — fixed in 1.0.1.76
NETGEAR R6400V2 Firmware: before 1.0.4.120 — fixed in 1.0.4.120
NETGEAR R6700V3 Firmware: before 1.0.4.120 — fixed in 1.0.4.120
NETGEAR R6900P Firmware: before 1.3.3.142 — fixed in 1.3.3.142
NETGEAR R7000: before 1.0.11.128 — fixed in 1.0.11.128
NETGEAR R7000P: before 1.3.3.142 — fixed in 1.3.3.142
NETGEAR R7100Lg Firmware: before 1.0.0.72 — fixed in 1.0.0.72
NETGEAR R7850 Firmware: before 1.0.5.76 — fixed in 1.0.5.76
NETGEAR R7900P Firmware: before 1.4.2.84 — fixed in 1.4.2.84
NETGEAR R7960P Firmware: before 1.4.2.84 — fixed in 1.4.2.84
NETGEAR R8000 Firmware: before 1.0.4.76 — fixed in 1.0.4.76
NETGEAR R8000P Firmware: before 1.4.2.84 — fixed in 1.4.2.84
NETGEAR R8300 Firmware: before 1.0.2.156 — fixed in 1.0.2.156
NETGEAR R8500 Firmware: before 1.0.2.156 — fixed in 1.0.2.156
NETGEAR Rax15 Firmware: before 1.0.4.100 — fixed in 1.0.4.100
NETGEAR Rax200 Firmware: before 1.0.5.132 — fixed in 1.0.5.132
NETGEAR Rax20 Firmware: before 1.0.4.100 — fixed in 1.0.4.100
NETGEAR Rax35V2 Firmware: before 1.0.4.100 — fixed in 1.0.4.100
NETGEAR Rax38V2 Firmware: before 1.0.4.100 — fixed in 1.0.4.100
NETGEAR Rax40V2 Firmware: before 1.0.4.100 — fixed in 1.0.4.100

How to fix

Upgrade to a fixed version: NETGEAR Cax80 Firmware 2.1.3.5; NETGEAR D6220 Firmware 1.0.0.76; Netgear D6400 1.0.0.108; NETGEAR D7000V2 Firmware 1.0.0.76; NETGEAR Dc112A Firmware 1.0.0.62; NETGEAR Dgn2200V4 Firmware 1.0.0.126; NETGEAR EX3700 1.0.0.94; NETGEAR Ex3800 Firmware 1.0.0.94; NETGEAR EX6120 1.0.0.66; NETGEAR Ex6130 Firmware 1.0.0.66; NETGEAR R6400 Firmware 1.0.1.76; NETGEAR R6400V2 Firmware 1.0.4.120. Check the vendor advisory for mitigations.

References

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