CVE-2025-12240 TOTOLINK A3300R cstecgi.cgi setDmzCfg buffer overflow

High 8.7 Published 27 Oct 2025 Updated 27 Oct 2025

Remote attackers can trigger a buffer overflow in the DMZ configuration handler of TOTOLINK A3300R routers, potentially leading to arbitrary code execution.

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-2025-12240?

CVE-2025-12240 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 security vulnerability has been detected in TOTOLINK A3300R 17.0.0cu.557_B20221024. This affects the function setDmzCfg of the file /cgi-bin/cstecgi.cgi. The manipulation of the argument ip leads to buffer overflow. It is possible to initiate the attack remotely. The exploit has been disclosed publicly and may be used.

Weakness: CWE-120, CWE-119

Which versions are affected by CVE-2025-12240?

It affects 1 product.

Products include Totolink A3300r Firmware.

How do I fix CVE-2025-12240?

No fix has been published for CVE-2025-12240 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-2025-12240 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-12240 exists.

All Totolink A3300r Firmware vulnerabilities

Sources

Also known as GHSA-j778-wm83-8cf7.