CVE-2026-90234Network attack vector

NFSv4 client hang via orphaned delegation state

Published Sep 17, 2026 · Updated Sep 18, 2026

Denial of service in the Linux NFSv4 client 4.0 through 7.2.5 allows remote attackers to hang NFSv4 access via a crafted server. The nfs_inode_set_delegation() error paths discard an unrecorded delegation without sending DELEGRETURN, leaving server and client state inconsistent. A malicious or compromised server must win a delegation recall and reopen race; revoked-state handling then loops indefinitely and blocks later NFSv4 RPCs.

CVSS severity7.5
High
EPSS probability0.61%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Get started

Summary

What happened

Denial of service in the Linux NFSv4 client 4.0 through 7.2.5 allows remote attackers to hang NFSv4 access via a crafted server. The nfs_inode_set_delegation() error paths discard an unrecorded delegation without sending DELEGRETURN, leaving server and client state inconsistent. A malicious or compromised server must win a delegation recall and reopen race; revoked-state handling then loops indefinitely and blocks later NFSv4 RPCs.

The record

CVE
CVE-2026-90234
Published
Sep 17, 2026
Updated
Sep 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.0
  2. Affected versionversion=ade04647dd56881e285983af3db702d56ee97e86 <220af23d863995091f0edeb1e6aa0945b3db8b37
  3. Affected versionversion=ade04647dd56881e285983af3db702d56ee97e86 <92533e49fe3c455088657b862cf3562260c0ce25

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.0; version=ade04647dd56881e285983af3db702d56ee97e86 <220af23d863995091f0edeb1e6aa0945b3db8b37; version=ade04647dd56881e285983af3db702d56ee97e86 <92533e49fe3c455088657b862cf3562260c0ce25

Published CVSS scores

7.5GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Get started to see how Hinoki identifies affected software and validates exploitability in your environment.

Get started