CVE-2021-34991

Ex3700 Firmware vulnerability

CVSS

8.8

EPSS

5.7%

EPSS pct

92th

Exploited

No known

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 vendor

Netgear

Affected product

Ex3700 Firmware

CVSS vector

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

Weakness type (CWE)

CWE-121 — Stack-based Buffer Overflow
CWE-787 — Out-of-bounds Write

Published

2021-11-15

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable from an adjacent network, low attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to high impact to confidentiality, high impact to integrity, high impact to availability.

Its EPSS score of 5.7% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 92% of all scored CVEs.

Check your external exposure to CVE-2021-34991

Confirm whether Netgear Ex3700 Firmware is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2021-34991.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2021-34991

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