CVE-2021-40416Network attack vector

Unauthorized Get API access via permissive default

Published Jan 28, 2022 · Updated Apr 15, 2025

Improper access control in Reolink RLC-410W firmware 3.0.0.136_20121102 allows remote authenticated users to invoke omitted Get APIs via HTTP. The cgiserver.cgi cgi_check_ability function assigns permission value 7 when an API command lacks an explicit switch case, causing its bitwise permission test to authorize the command. A valid session is required for this flaw alone; Talos reports that chaining a separate authentication flaw makes the affected Get APIs reachable without authentication.

CVSS severity8.8
High
EPSS probability0.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Reolink RLC-410W firmware 3.0.0.136_20121102 allows remote authenticated users to invoke omitted Get APIs via HTTP. The cgiserver.cgi cgi_check_ability function assigns permission value 7 when an API command lacks an explicit switch case, causing its bitwise permission test to authorize the command. A valid session is required for this flaw alone; Talos reports that chaining a separate authentication flaw makes the affected Get APIs reachable without authentication.

The record

CVE
CVE-2021-40416
Published
Jan 28, 2022
Updated
Apr 15, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-284
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 28, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 2025Record 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 vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.1Cisco TalosCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/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.

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No observations available

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

Weakness, pattern, technique

CWE-284Improper Access Control

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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