CVE-2025-40080 nbd: restrict sockets to TCP and UDP

Not scored Published 28 Oct 2025 Updated 15 Oct 2026

The Linux kernel NBD module allowed unsupported socket types, potentially causing denial of service; attackers with local access could exploit this.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Local or same network only
Victim action needed: Not needed
Fix: Available

What is CVE-2025-40080?

CVE-2025-40080 is a vulnerability in Linux, published on 28 Oct 2025. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

nbd: restrict sockets to TCP and UDP

Recently, syzbot started to abuse NBD with all kinds of sockets.

Commit cf1b2326b734 ("nbd: verify socket is supported during setup") made sure the socket supported a shutdown() method.

Explicitely accept TCP and UNIX stream sockets.

Which versions are affected by CVE-2025-40080?

How do I fix CVE-2025-40080?

Apply the vendor's patch.

Is CVE-2025-40080 being exploited?

There is no known exploitation of CVE-2025-40080 in the wild and no public exploit code.

Sources

Also known as AZL-68879, BELL-CVE-2025-40080, DEBIAN-CVE-2025-40080, GHSA-mp9c-x94p-8jh7, ROOT-OS-DEBIAN-11-CVE-2025-40080, ROOT-OS-DEBIAN-12-CVE-2025-40080 and 4 more.