CVE-2026-31712Network attack vector

Authenticated kernel out-of-bounds read via undersized ACE

Published May 1, 2026 · Updated May 1, 2026

Out-of-bounds reads in Linux Kernel ksmbd allow remote authenticated users to trigger kernel memory faults through a crafted file DACL. Both ACE-walk loops in smb_check_perm_dacl() accept an ace->size smaller than the smb_ace layout, then read access_req and sid beyond the declared ACE. Reachability requires SMB credentials and ACL-setting permission on a controlled file; a later CREATE processes the DACL, with no memory data returned to the client.

CVSS severity8.3
High
EPSS probability0.32%
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 reads in Linux Kernel ksmbd allow remote authenticated users to trigger kernel memory faults through a crafted file DACL. Both ACE-walk loops in smb_check_perm_dacl() accept an ace->size smaller than the smb_ace layout, then read access_req and sid beyond the declared ACE. Reachability requires SMB credentials and ACL-setting permission on a controlled file; a later CREATE processes the DACL, with no memory data returned to the client.

The record

CVE
CVE-2026-31712
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-787, T1190
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. May 1, 2026CVE publishedPublication date reported by the CVE source.
  2. May 1, 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=5.15
  2. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <151b1799861fde38087c08f613abc2843ef597b0
  3. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <90089584b2e25c4510b7b987387b4405f0673ece
  4. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c
  5. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <d07b26f39246a82399661936dd0c853983cfade7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.15; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <151b1799861fde38087c08f613abc2843ef597b0; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <90089584b2e25c4510b7b987387b4405f0673ece; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <d07b26f39246a82399661936dd0c853983cfade7

Published CVSS scores

8.3kernel.orgCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

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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