CVE-2025-12239 TOTOLINK A3300R cstecgi.cgi setDdnsCfg buffer overflow

High 8.7 Published 27 Oct 2025 Updated 27 Oct 2025

Remote attackers can exploit a buffer overflow in the DDNS configuration handler of TOTOLINK A3300R routers to execute arbitrary code or cause denial of service.

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

What is CVE-2025-12239?

CVE-2025-12239 is a high-severity memory corruption vulnerability in Totolink A3300r Firmware, published on 27 Oct 2025. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

A weakness has been identified in TOTOLINK A3300R 17.0.0cu.557_B20221024. The impacted element is the function setDdnsCfg of the file /cgi-bin/cstecgi.cgi. Executing manipulation can lead to buffer overflow. The attack may be performed from remote. The exploit has been made available to the public and could be exploited.

Weakness: CWE-120, CWE-119

Which versions are affected by CVE-2025-12239?

It affects 1 product.

Products include Totolink A3300r Firmware.

How do I fix CVE-2025-12239?

No fix has been published for CVE-2025-12239 yet. Limit exposure of the affected software until one is available.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2025-12239 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-12239 exists.

All Totolink A3300r Firmware vulnerabilities

Sources

Also known as GHSA-mqw5-rf2x-2m89.