CVE-2026-43046

Kernel crash via unvalidated btrfs root item

Published May 1, 2026 · Updated May 1, 2026

Reachable assertion in Linux Kernel allows local users to crash the kernel by mounting corrupted btrfs metadata during recovery. The btrfs tree checker accepts a root item whose drop_progress.objectid is nonzero while drop_level is zero, so relocation recovery reaches BUG_ON(level == 0) in merge_reloc_root() or btrfs_drop_snapshot(). Exploitation requires local ability to supply and mount malformed btrfs metadata; the bounded consequence is an availability-only kernel crash during mount-time recovery.

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

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Reachable assertion in Linux Kernel allows local users to crash the kernel by mounting corrupted btrfs metadata during recovery. The btrfs tree checker accepts a root item whose drop_progress.objectid is nonzero while drop_level is zero, so relocation recovery reaches BUG_ON(level == 0) in merge_reloc_root() or btrfs_drop_snapshot(). Exploitation requires local ability to supply and mount malformed btrfs metadata; the bounded consequence is an availability-only kernel crash during mount-time recovery.

The record

CVE
CVE-2026-43046
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-617, T1499.004
Attack vector
local
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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <295f8075d00442d71dc9ccae421ace1c0d2d9224
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <53ceedd1eb6280ca8359664e0226983eded2ed73
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <850de3d87f4720b71ccdcd44f4aa57e46b53a3f3
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ac68a9a8e481ab1becaed29d6d23087dac3de15d
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b17b79ff896305fd74980a5f72afec370ee88ca4
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bedaf7d0b9d793e116f16b4d9a7dbc94bcc80443
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <de585ee18dd5601745f65a60fef7b7ceebd78c83

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <295f8075d00442d71dc9ccae421ace1c0d2d9224; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <53ceedd1eb6280ca8359664e0226983eded2ed73; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <850de3d87f4720b71ccdcd44f4aa57e46b53a3f3; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ac68a9a8e481ab1becaed29d6d23087dac3de15d; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <b17b79ff896305fd74980a5f72afec370ee88ca4; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <bedaf7d0b9d793e116f16b4d9a7dbc94bcc80443; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <de585ee18dd5601745f65a60fef7b7ceebd78c83

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

CWE-617Reachable Assertion
T1499.004Application or System Exploitation

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo