CVE-2026-43350Network attack vector

Out-of-bounds read via prefix-matched NFS mode SID

Published May 8, 2026 · Updated May 8, 2026

Out-of-bounds read in the Linux Kernel SMB client allows remote attackers to misinterpret permission data via a malicious SMB server. In parse_dacl(), compare_sids() accepts a two-subauthority ACE SID as sid_unix_NFS_mode because it compares only the shorter SID, then reads sub_auth[2] four bytes beyond the ACE. The trigger requires a user to connect the client to an attacker-controlled SMB server, where the malformed DACL becomes incorrect file-mode data.

CVSS severity7.6
High
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in the Linux Kernel SMB client allows remote attackers to misinterpret permission data via a malicious SMB server. In parse_dacl(), compare_sids() accepts a two-subauthority ACE SID as sid_unix_NFS_mode because it compares only the shorter SID, then reads sub_auth[2] four bytes beyond the ACE. The trigger requires a user to connect the client to an attacker-controlled SMB server, where the malformed DACL becomes incorrect file-mode data.

The record

CVE
CVE-2026-43350
Published
May 8, 2026
Updated
May 8, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 8, 2026CVE publishedPublication date reported by the CVE source.
  2. May 8, 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=5.4
  2. Affected versionversion=e2f8fbfb8d09c06decde162090fac3ee220aa280 <2757ad3e4b6f9e0fed4c7739594e702abc5cab21
  3. Affected versionversion=e2f8fbfb8d09c06decde162090fac3ee220aa280 <38a69f08ee82c450d3e4168707fff2e317dc3ff7
  4. Affected versionversion=e2f8fbfb8d09c06decde162090fac3ee220aa280 <b53b8e98c23310294fc45fc686db5ee860311896
  5. Affected versionversion=e2f8fbfb8d09c06decde162090fac3ee220aa280 <c8eef12af1cc73031639ea7cf16e0b10e2536b0b
  6. Affected versionversion=e2f8fbfb8d09c06decde162090fac3ee220aa280 <f8488c07bea2431ee12a6067d736578064fa46b4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.4; version=e2f8fbfb8d09c06decde162090fac3ee220aa280 <2757ad3e4b6f9e0fed4c7739594e702abc5cab21; version=e2f8fbfb8d09c06decde162090fac3ee220aa280 <38a69f08ee82c450d3e4168707fff2e317dc3ff7; version=e2f8fbfb8d09c06decde162090fac3ee220aa280 <b53b8e98c23310294fc45fc686db5ee860311896; version=e2f8fbfb8d09c06decde162090fac3ee220aa280 <c8eef12af1cc73031639ea7cf16e0b10e2536b0b; version=e2f8fbfb8d09c06decde162090fac3ee220aa280 <f8488c07bea2431ee12a6067d736578064fa46b4

Published CVSS scores

7.6Linux kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/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.

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No observations available

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

Weakness, pattern, technique

T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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