CVE-2026-43193

Service interruption via nfs4_file reference leak

Published May 6, 2026 · Updated May 6, 2026

Reference-count leakage in Linux Kernel 6.19 through 6.19.5 allows local users to interrupt service through NFS directory delegation requests. The nfsd_get_dir_deleg function obtains an nfs4_file reference in fp but returns without releasing it, so repeated calls retain kernel objects. Low-privilege access and reachability of the NFSv4 GET_DIR_DELEGATION path are required; published scoring reports availability loss without confidentiality or integrity impact.

CVSS severity5.5
Medium
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reference-count leakage in Linux Kernel 6.19 through 6.19.5 allows local users to interrupt service through NFS directory delegation requests. The nfsd_get_dir_deleg function obtains an nfs4_file reference in fp but returns without releasing it, so repeated calls retain kernel objects. Low-privilege access and reachability of the NFSv4 GET_DIR_DELEGATION path are required; published scoring reports availability loss without confidentiality or integrity impact.

The record

CVE
CVE-2026-43193
Published
May 6, 2026
Updated
May 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=6.19
  2. Affected versionversion=8b99f6a8c116f664a6788737705f6da2772cc96a <0d8362e15aad5b5c1d6a65bb23ac6c45ccf881f3
  3. Affected versionversion=8b99f6a8c116f664a6788737705f6da2772cc96a <789477b849394afdb60507924d65f7ef18f078ce

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=6.19; version=8b99f6a8c116f664a6788737705f6da2772cc96a <0d8362e15aad5b5c1d6a65bb23ac6c45ccf881f3; version=8b99f6a8c116f664a6788737705f6da2772cc96a <789477b849394afdb60507924d65f7ef18f078ce

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/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.

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

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

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

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Your stack

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