CVE-2025-66620 Columbia Weather Systems MicroServer Command Shell in Externally Accessible Directory

High 8.6 Published 7 Jan 2026 Updated 7 Jan 2026

An attacker with admin access can exploit an unused webshell to gain shell access, modify data, and establish persistence on the MicroServer.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: None listed

What is CVE-2025-66620?

CVE-2025-66620 is a high-severity command injection vulnerability in Columbia Weather Systems MicroServer, published on 7 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

An unused webshell in MicroServer allows unlimited login attempts, with sudo rights on certain files and directories. An attacker with admin access to MicroServer can gain limited shell access, enabling persistence through reverse shells, and the ability to modify or remove data stored in the file system.

Weakness: CWE-553

Which versions are affected by CVE-2025-66620?

It affects 1 product.

Products include Columbiaweather Weather Microserver Firmware.

How do I fix CVE-2025-66620?

No fix has been published for CVE-2025-66620 yet. Limit exposure of the affected software until one is available.

Upgrade, and pass arguments to programs as a list instead of through a shell. More about Command injection.

Is CVE-2025-66620 being exploited?

There is no known exploitation of CVE-2025-66620 in the wild and no public exploit code.

Sources

Also known as GHSA-mh3m-m8m5-x43f.