CVE-2026-46159

Kernel heap disclosure via Btrfs ioctl race

Published May 28, 2026 · Updated May 28, 2026

Information disclosure in Linux Kernel Btrfs allows local users to read uninitialized kernel heap data through a filesystem ioctl. btrfs_ioctl_space_info() releases groups_sem between its counting and filling passes, then copy_to_user() copies the original allocation size when concurrent block-group removal leaves fewer filled entries. Exposure requires local access to a mounted Btrfs filesystem and concurrent block-group removal; returned trailing bytes contain residual kernel heap data.

CVSS severity4.7
Medium
EPSS probability0.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Linux Kernel Btrfs allows local users to read uninitialized kernel heap data through a filesystem ioctl. btrfs_ioctl_space_info() releases groups_sem between its counting and filling passes, then copy_to_user() copies the original allocation size when concurrent block-group removal leaves fewer filled entries. Exposure requires local access to a mounted Btrfs filesystem and concurrent block-group removal; returned trailing bytes contain residual kernel heap data.

The record

CVE
CVE-2026-46159
Published
May 28, 2026
Updated
May 28, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-367, T1005
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=2.6.34
  2. Affected versionversion=7fde62bffb576d384ea49a3aed3403d5609ee5bc <4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3
  3. Affected versionversion=7fde62bffb576d384ea49a3aed3403d5609ee5bc <5d12e0ab009ade48c1bff9324fd9bea2c773d088
  4. Affected versionversion=7fde62bffb576d384ea49a3aed3403d5609ee5bc <973e57c726c1f8e77259d1c8e519519f1e9aea77
  5. Affected versionversion=7fde62bffb576d384ea49a3aed3403d5609ee5bc <d09d67d5de577cedae3de9497dff217e0ac8b641
  6. Affected versionversion=7fde62bffb576d384ea49a3aed3403d5609ee5bc <f5ee467b56764964027c361641f64953fc0f8f9a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.34; version=7fde62bffb576d384ea49a3aed3403d5609ee5bc <4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3; version=7fde62bffb576d384ea49a3aed3403d5609ee5bc <5d12e0ab009ade48c1bff9324fd9bea2c773d088; version=7fde62bffb576d384ea49a3aed3403d5609ee5bc <973e57c726c1f8e77259d1c8e519519f1e9aea77; version=7fde62bffb576d384ea49a3aed3403d5609ee5bc <d09d67d5de577cedae3de9497dff217e0ac8b641; version=7fde62bffb576d384ea49a3aed3403d5609ee5bc <f5ee467b56764964027c361641f64953fc0f8f9a

Published CVSS scores

4.7NIST NVDCVSS:3.1/AV:L/AC:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
T1005Data from Local System

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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