CVE-2021-40419Public exploitNetwork attack vector

Unauthenticated firmware replacement via factory debug service

Published Jan 28, 2022 · Updated Apr 15, 2025

Firmware update flaw in the factory binary in Reolink RLC-410W 3.0.0.136_20121102 allows remote attackers to replace firmware. The wait_for_connection function trusts a four-byte UDP marker on port 2009, records the sender address, and connects back on port 9123 without authentication. Any network host that can reach the listener can submit firmware that is installed after only a CRC check, enabling persistent control of camera operation.

CVSS severity10.0
Critical
EPSS probability1.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Firmware update flaw in the factory binary in Reolink RLC-410W 3.0.0.136_20121102 allows remote attackers to replace firmware. The wait_for_connection function trusts a four-byte UDP marker on port 2009, records the sender address, and connects back on port 9123 without authentication. Any network host that can reach the listener can submit firmware that is installed after only a CRC check, enabling persistent control of camera operation.

The record

CVE
CVE-2021-40419
Published
Jan 28, 2022
Updated
Apr 15, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-489, T1495
Attack vector
network
Privileges
unauthenticated

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 privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

10.0Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-489Leftover Debug Code
T1495Firmware Corruption

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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