CVE-2021-3166Public exploitNetwork attack vector

Persistent service outage via arbitrary firmware upload

Published Jan 18, 2021 · Updated Aug 3, 2024

Arbitrary file upload in ASUS DSL-N14U-B1 firmware 1.1.2.3_805 allows remote attackers to cause persistent service outages via a crafted firmware update. The firmware upgrade handler accepts arbitrary content when the uploaded filename is Settings_DSL-N14U-B1.trx and processes it as a legitimate update, triggering shutdown measures across services. The attack requires network reachability but no authentication or user interaction, and the documented consequence is a persistent denial of service without confidentiality or integrity impact.

CVSS severity7.5
High
EPSS probability2.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Arbitrary file upload in ASUS DSL-N14U-B1 firmware 1.1.2.3_805 allows remote attackers to cause persistent service outages via a crafted firmware update. The firmware upgrade handler accepts arbitrary content when the uploaded filename is Settings_DSL-N14U-B1.trx and processes it as a legitimate update, triggering shutdown measures across services. The attack requires network reachability but no authentication or user interaction, and the documented consequence is a persistent denial of service without confidentiality or integrity impact.

The record

CVE
CVE-2021-3166
Published
Jan 18, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-434, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 18, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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 vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-434Unrestricted Upload of File with Dangerous Type
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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