CVE-2021-40556 Memory corruption in n/a

High 8.8 Published 6 Oct 2022 Updated 4 Aug 2024

Authenticated attackers can trigger a stack overflow in the httpd service to execute arbitrary commands remotely on ASUS RT-AX56U routers.

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-2021-40556?

CVE-2021-40556 is a high-severity memory corruption vulnerability in n/a, published on 6 Oct 2022. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

A stack overflow vulnerability exists in the httpd service in ASUS RT-AX56U Router Version 3.0.0.4.386.44266. This vulnerability is caused by the strcat function called by "caupload" input handle function allowing the user to enter 0xFFFF bytes into the stack. This vulnerability allows an attacker to execute commands remotely. The vulnerability requires authentication.

Weakness: CWE-787

Which versions are affected by CVE-2021-40556?

It affects 1 product.

Products include Asus Rt-Ax56u Firmware.

How do I fix CVE-2021-40556?

No fix has been published for CVE-2021-40556 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-2021-40556 being exploited?

There is no known exploitation of CVE-2021-40556 in the wild and no public exploit code.

Sources

Also known as GHSA-9v8q-97m7-4x6q.