CVE-2025-3666Public exploitNetwork attack vector

Unauthenticated DDNS configuration changes via missing access checks

Published Apr 16, 2025 · Updated Apr 16, 2025

Improper access control in TOTOLINK A3700R 9.1.2u.5822_B20200513 allows remote attackers to alter DDNS settings via setDdnsCfg. The /cgi-bin/cstecgi.cgi handler invokes setDdnsCfg for unauthenticated requests instead of enforcing administrative access. Network reachability to the management interface is sufficient; successful exploitation changes router configuration without reported code execution or data disclosure.

CVSS severity6.9
Medium
EPSS probability0.64%
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 TOTOLINK A3700R 9.1.2u.5822_B20200513 allows remote attackers to alter DDNS settings via setDdnsCfg. The /cgi-bin/cstecgi.cgi handler invokes setDdnsCfg for unauthenticated requests instead of enforcing administrative access. Network reachability to the management interface is sufficient; successful exploitation changes router configuration without reported code execution or data disclosure.

The record

CVE
CVE-2025-3666
Published
Apr 16, 2025
Updated
Apr 16, 2025
Vendor
TOTOLINK
Product
A3700R
Classifications
CWE-284, CWE-266, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 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?

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

  1. Affected versionversion=9.1.2u.5822_B20200513

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

TOTOLINK · A3700Rversion=9.1.2u.5822_B20200513

Published CVSS scores

5.3VulDB CNACVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
5.3VulDB CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
6.9VulDB CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
5.0VulDB CNAAV:N/AC:L/Au:N/C:N/I:P/A:N

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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control
CWE-266Incorrect Privilege Assignment
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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