CVE-2021-40867Public exploit

Administrator access via source-IP session race

Published Sep 13, 2021 · Updated Aug 4, 2024

Authentication hijacking in NETGEAR smart switches before their fixed firmware versions allows remote attackers to gain administrator access. The home_loginStatus handler selects an authentication result file using only the client IP address and a guessable browser-type value, then returns session bootstrap data to the requester that wins the polling race. Exploitation requires the same apparent source IP as an administrator during login and winning the roughly one-second race, after which the switch web interface grants full administrative control.

CVSS severity7.1
High
EPSS probability1.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication hijacking in NETGEAR smart switches before their fixed firmware versions allows remote attackers to gain administrator access. The home_loginStatus handler selects an authentication result file using only the client IP address and a guessable browser-type value, then returns session bootstrap data to the requester that wins the polling race. Exploitation requires the same apparent source IP as an administrator during login and winning the roughly one-second race, after which the switch web interface grants full administrative control.

The record

CVE
CVE-2021-40867
Published
Sep 13, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-290, T1190
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 13, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.1NIST NVDCVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
5.4NIST NVDAV:A/AC:M/Au:N/C:P/I:P/A:P
7.8MITRECVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

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 exploitPublished

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
T1190Exploit Public-Facing Application

Public exploit references

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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