CVE-2026-31519

Filesystem abort via unset orphan-cleanup state

Published Apr 22, 2026 · Updated Apr 22, 2026

A race condition in Linux Kernel Btrfs allows local users to abort a mounted filesystem through concurrent subvolume operations. The create_subvol path leaves BTRFS_ROOT_ORPHAN_CLEANUP unset, so delayed inode eviction can race the first orphan cleanup and make btrfs_lookup_dentry return ENOENT for a valid subvolume. A local account with write access to a Btrfs subvolume is required; the resulting negative dentry can make the subvolume inaccessible and a conflicting create can abort the filesystem.

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

A race condition in Linux Kernel Btrfs allows local users to abort a mounted filesystem through concurrent subvolume operations. The create_subvol path leaves BTRFS_ROOT_ORPHAN_CLEANUP unset, so delayed inode eviction can race the first orphan cleanup and make btrfs_lookup_dentry return ENOENT for a valid subvolume. A local account with write access to a Btrfs subvolume is required; the resulting negative dentry can make the subvolume inaccessible and a conflicting create can abort the filesystem.

The record

CVE
CVE-2026-31519
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-476, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2ec578e6452138ab76f6c9a9c18711fcd197649f
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5131fa077f9bb386a1b901bf5b247041f0ec8f80
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <696683f214495db3cdacab9a713efaaced8660f8
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a41a9b8d19a98b45591528c6e54d31cc66271d1e
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c57276ced3c3207f42182dfa2f0d8e860357e111
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d43da8de0ed376abafbad8a245a1835e8f66cb0f

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2ec578e6452138ab76f6c9a9c18711fcd197649f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <5131fa077f9bb386a1b901bf5b247041f0ec8f80; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <696683f214495db3cdacab9a713efaaced8660f8; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <a41a9b8d19a98b45591528c6e54d31cc66271d1e; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c57276ced3c3207f42182dfa2f0d8e860357e111; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d43da8de0ed376abafbad8a245a1835e8f66cb0f

Published CVSS scores

5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.8SUSECVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5Canonical UbuntuCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.7Amazon LinuxCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
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-476NULL Pointer Dereference
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

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Your stack

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