VulnerabilityPublished 28 Oct 2025Updated 10 Nov 2026

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

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in c365e8f20f4201d873a70385bd919f0fb531e960 : update Linux kernel when convenient.

Data as of 10 Nov 2026, 15:03 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Patch: Available – fixed in c365e8f20f4201d873a70385bd919f0fb531e960, 808e2335bc1cf2293b9e36ccc94c267c81509c71, 37ad11f20e164c23ce827dd455b42c0fdd29685c +5

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=4.14.152 <4.15 >=4.19.82 <4.20 >=5.3.9 <5.4	Fixed in c365e8f20f4201d873a70385bd919f0fb531e960 808e2335bc1cf2293b9e36ccc94c267c81509c71 37ad11f20e164c23ce827dd455b42c0fdd29685c 9f7c02e031570e8291a63162c6c046dc15ff85b0 5.4 4f9e6ff6319dbcebea64b50af0304cf0ad7e97e7 4.20 4.15
LinuxLinux	Affected =5.4	Fixed in–

AI-suggested

The issue has been fixed in Linux kernel versions 4.15, 4.20, 5.4, and later. Users should upgrade to these or newer versions to remediate the vulnerability.

Description

A vulnerability in the Linux kernel's Network Block Device (nbd) subsystem allowed the use of unsupported socket types. This issue was addressed by restricting nbd sockets to only TCP and UNIX stream sockets, ensuring the socket supports the shutdown() method. The flaw affected multiple Linux kernel versions prior to the fix.

Impact

The vulnerability could allow misuse of the nbd subsystem by using unsupported socket types, potentially leading to unexpected behavior or resource abuse. However, no known exploits in the wild have been reported.

Summary

The Linux kernel's nbd subsystem previously accepted various socket types, which syzbot began abusing. The vulnerability was mitigated by a commit that verifies the socket type during setup, explicitly allowing only TCP and UNIX stream sockets that support the shutdown() method. This restricts the socket usage to intended protocols, preventing misuse.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Nov 2026, 15:03 UTC

Technical details

References

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