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

Severity: unknown
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-28 · updated 2026-10-19

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.

Affected products

Linux kernel: from 4.14.152 before 4.15; from 4.19.82 before 4.20; from 5.3.9 before 5.4; 5.4 — fixed in 4.15, 4.20, 5.4, 6.18

How to fix

Upgrade to a fixed version: Linux kernel 4.15, 4.20, 5.4, 6.18. Check the vendor advisory for mitigations.

References

https://git.kernel.org/stable/c/37ad11f20e164c23ce827dd455b42c0fdd29685c
https://git.kernel.org/stable/c/4f9e6ff6319dbcebea64b50af0304cf0ad7e97e7
https://git.kernel.org/stable/c/808e2335bc1cf2293b9e36ccc94c267c81509c71
https://git.kernel.org/stable/c/9f7c02e031570e8291a63162c6c046dc15ff85b0
https://git.kernel.org/stable/c/c365e8f20f4201d873a70385bd919f0fb531e960
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-457936.html

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