CVE-2026-43359

Filesystem denial of service via late overflow check

Published May 8, 2026 · Updated May 8, 2026

Denial of service in Linux kernel Btrfs allows local users to force a mounted filesystem into read-only mode through an ioctl. The set received ioctl starts metadata updates before checking whether inserting BTRFS_UUID_KEY_RECEIVED_SUBVOL will overflow a UUID-tree item, so repeated UUID reuse forces a transaction abort. Ownership of the targeted subvolume is sufficient without CAP_SYS_ADMIN; the abort preserves metadata consistency but interrupts writes by making the filesystem read-only.

CVSS severityUnavailable
Unscored
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

Denial of service in Linux kernel Btrfs allows local users to force a mounted filesystem into read-only mode through an ioctl. The set received ioctl starts metadata updates before checking whether inserting BTRFS_UUID_KEY_RECEIVED_SUBVOL will overflow a UUID-tree item, so repeated UUID reuse forces a transaction abort. Ownership of the targeted subvolume is sufficient without CAP_SYS_ADMIN; the abort preserves metadata consistency but interrupts writes by making the filesystem read-only.

The record

CVE
CVE-2026-43359
Published
May 8, 2026
Updated
May 8, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-191, T1499
Attack vector
local
Privileges
authenticated

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

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=3.12
  2. Affected versionversion=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <2e57b8cac2ba0d38aac76c1ecdfd8b899e3581a5
  3. Affected versionversion=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <41fb97353ff58fa4f31904c343fc8e3df2f7517d
  4. Affected versionversion=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <87f2c46003fce4d739138aab4af1942b1afdadac
  5. Affected versionversion=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <b19c0465e4daad5aa8f60552ea0578cf31a11b1e
  6. Affected versionversion=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <b9914db13ac15aca3b74544c0bb1a2e0dad1f174
  7. Affected versionversion=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <d11aefe654a04fc41996d254748d6a38b6b0a7be

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=3.12; version=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <2e57b8cac2ba0d38aac76c1ecdfd8b899e3581a5; version=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <41fb97353ff58fa4f31904c343fc8e3df2f7517d; version=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <87f2c46003fce4d739138aab4af1942b1afdadac; version=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <b19c0465e4daad5aa8f60552ea0578cf31a11b1e; version=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <b9914db13ac15aca3b74544c0bb1a2e0dad1f174; version=dd5f9615fc5c5e8d3751aab3a17b92768fb1ce70 <d11aefe654a04fc41996d254748d6a38b6b0a7be

Published CVSS scores

No CVSS assessment is available in this record.

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-191Integer Underflow (Wrap or Wraparound)
T1499Endpoint Denial of Service

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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