CVE-2026-46139

chmod failure via uninitialized ACL reserved field

Published May 28, 2026 · Updated May 28, 2026

Use of uninitialized data in the Linux kernel SMB client allows local users to make chmod operations fail with EINVAL on CIFS mounts. The build_sec_desc() function allocates the security descriptor with kmalloc() and never writes the two-byte Sbz2 reserved field, so slab contents enter the ACL. The failure occurs when a local user changes permissions on a CIFS mount and the reserved bytes are nonzero; Samba rejects the descriptor, interrupting only that chmod request.

CVSS severity5.5
Medium
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use of uninitialized data in the Linux kernel SMB client allows local users to make chmod operations fail with EINVAL on CIFS mounts. The build_sec_desc() function allocates the security descriptor with kmalloc() and never writes the two-byte Sbz2 reserved field, so slab contents enter the ACL. The failure occurs when a local user changes permissions on a CIFS mount and the reserved bytes are nonzero; Samba rejects the descriptor, interrupting only that chmod request.

The record

CVE
CVE-2026-46139
Published
May 28, 2026
Updated
May 28, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-908
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 28, 2026CVE publishedPublication date reported by the CVE source.
  2. May 28, 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=1593ddb37bd124c131fe635397df68e854a03108 <4c3ed344a970aad51388ac3b0145b98318f0e21f
  2. Affected versionversion=191f2f444745087c3c51fd6042a0e25f42315ab0
  3. Affected versionversion=6.12.23 <6.12.88
  4. Affected versionversion=6.13.11 <6.14
  5. Affected versionversion=6.14
  6. Affected versionversion=62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d <5e489c6c47a2ac15edbaca153b9348e42c1eacab
  7. Affected versionversion=62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d <9bdb2ca31368b7671949dfb94a5d57ffccd01edd
  8. Affected versionversion=62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d <be1ef9512a3f5a755895c24f31b334342f4aa15b
  9. Affected versionversion=da087905e3270e2291c0afae39a28e7d183e5ec3 <941a1e6eb35440336913afc88a82103291956d5d

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1593ddb37bd124c131fe635397df68e854a03108 <4c3ed344a970aad51388ac3b0145b98318f0e21f; version=191f2f444745087c3c51fd6042a0e25f42315ab0; version=6.12.23 <6.12.88; version=6.13.11 <6.14; version=6.14; version=62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d <5e489c6c47a2ac15edbaca153b9348e42c1eacab; version=62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d <9bdb2ca31368b7671949dfb94a5d57ffccd01edd; version=62e7dd0a39c2d0d7ff03274c36df971f1b3d2d0d <be1ef9512a3f5a755895c24f31b334342f4aa15b; version=da087905e3270e2291c0afae39a28e7d183e5ec3 <941a1e6eb35440336913afc88a82103291956d5d

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.

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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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-908Use of Uninitialized Resource

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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