CVE-2021-34991

Root code execution via UPnP uuid overflow

Published Nov 15, 2021 · Updated Aug 4, 2024

Stack-based buffer overflow in NETGEAR R6400v2 1.0.4.106_10.0.80 allows network-adjacent attackers to execute code as root. The UPnP service on TCP port 5000 copies an unchecked uuid request header into a fixed-length stack buffer. Exploitation requires local-area-network access but no authentication and grants control of the router with root privileges.

CVSS severity8.8
High
EPSS probability5.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in NETGEAR R6400v2 1.0.4.106_10.0.80 allows network-adjacent attackers to execute code as root. The UPnP service on TCP port 5000 copies an unchecked uuid request header into a fixed-length stack buffer. Exploitation requires local-area-network access but no authentication and grants control of the router with root privileges.

The record

CVE
CVE-2021-34991
Published
Nov 15, 2021
Updated
Aug 4, 2024
Vendor
NETGEAR
Product
R6400v2
Classifications
CWE-787, CWE-121, T1210
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1.0.4.106_10.0.80

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

NETGEAR · R6400v2version=1.0.4.106_10.0.80

Published CVSS scores

8.8Zero Day InitiativeCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.8NIST National Vulnerability DatabaseCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.3NIST National Vulnerability DatabaseAV:A/AC:L/Au:N/C:C/I:C/A:C

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-121Stack-based Buffer Overflow
T1210Exploitation of Remote Services

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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