CVE-2026-31586Public exploit

Kernel crash via premature blk-cgroup reference release

Published Apr 24, 2026 · Updated Apr 24, 2026

Use-after-free in the Linux kernel blk-cgroup writeback release path allows local users to crash the kernel through a narrow race. cgwb_release_workfn() drops the wb->blkcg_css reference with css_put() before blkcg_unpin_online() writes through that pointer, so asynchronous CSS cleanup can free the blkcg first. Reaching the invalid write requires local low-privileged access and precise timing during cgroup writeback release; the demonstrated consequence is a kernel crash.

CVSS severity7.8
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in the Linux kernel blk-cgroup writeback release path allows local users to crash the kernel through a narrow race. cgwb_release_workfn() drops the wb->blkcg_css reference with css_put() before blkcg_unpin_online() writes through that pointer, so asynchronous CSS cleanup can free the blkcg first. Reaching the invalid write requires local low-privileged access and precise timing during cgroup writeback release; the demonstrated consequence is a kernel crash.

The record

CVE
CVE-2026-31586
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 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 <50879a3c1faf06e661090015d59e2127255cff27
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <67cb119d32f35e32acd0393bbeb318b2bb1fdafe
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dfc8292a1d6782c76b626315605e0585a5a18447
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ea3af09eb87d8f8708c66747fcf1a2762902e839

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <50879a3c1faf06e661090015d59e2127255cff27; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <67cb119d32f35e32acd0393bbeb318b2bb1fdafe; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <dfc8292a1d6782c76b626315605e0585a5a18447; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <ea3af09eb87d8f8708c66747fcf1a2762902e839

Published CVSS scores

7.8kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application or System Exploitation

Public exploit references

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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