CVE-2025-3666 TOTOLINK A3700R cstecgi.cgi setDdnsCfg access control

Medium 6.9 Published 16 Apr 2025 Updated 16 Apr 2025

Remote attackers can bypass access controls to modify DDNS settings on TOTOLINK A3700R routers due to improper authorization checks.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2025-3666?

CVE-2025-3666 is a medium-severity missing authorization vulnerability in TOTOLINK A3700R, published on 16 Apr 2025. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A vulnerability was found in TOTOLINK A3700R 9.1.2u.5822_B20200513 and classified as critical. Affected by this issue is the function setDdnsCfg of the file /cgi-bin/cstecgi.cgi. The manipulation leads to improper access controls. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Weakness: CWE-284, CWE-266

Which versions are affected by CVE-2025-3666?

It affects 1 product.

Products include Totolink A3700r Firmware.

How do I fix CVE-2025-3666?

No fix has been published for CVE-2025-3666 yet. Limit exposure of the affected software until one is available.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2025-3666 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-3666 exists.

Sources

Also known as GHSA-pvmj-4jf2-h6jf.