CVE-2024-49867

Kernel crash via btrfs unmount use-after-free

Published Oct 21, 2024 · Updated Aug 5, 2026

Use-after-free in Linux btrfs allows local users to crash the kernel by racing fixup work with filesystem unmount. The close_ctree() path stops and frees the cleaner kthread before btrfs_stop_all_workers() drains fixup work, so a worker performing delayed iput dereferences the freed task_struct while waking the cleaner. Reachability requires a mounted btrfs filesystem, an in-flight fixup worker, and concurrent unmount; the confirmed consequence is a kernel crash.

CVSS severity7.8
High
EPSS probability0.30%
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 Linux btrfs allows local users to crash the kernel by racing fixup work with filesystem unmount. The close_ctree() path stops and frees the cleaner kthread before btrfs_stop_all_workers() drains fixup work, so a worker performing delayed iput dereferences the freed task_struct while waking the cleaner. Reachability requires a mounted btrfs filesystem, an in-flight fixup worker, and concurrent unmount; the confirmed consequence is a kernel crash.

The record

CVE
CVE-2024-49867
Published
Oct 21, 2024
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 21, 2024CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=5.4.22 <5.4.285
  2. Affected versionversion=5.5.6 <5.6
  3. Affected versionversion=5.6
  4. Affected versionversion=6026fd9da213daab95469356fe7fdcf29ae1a296
  5. Affected versionversion=7a97311de48d56af6db4c5819f95faf9b0b23b1a <a71349b692ab34ea197949e13e3cc42570fe73d9
  6. Affected versionversion=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <41fd1e94066a815a7ab0a7025359e9b40e4b3576
  7. Affected versionversion=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <4c98fe0dfa2ae83c4631699695506d8941db4bfe
  8. Affected versionversion=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <65d11eb276836d49003a8060cf31fa2284ad1047
  9. Affected versionversion=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <70b60c8d9b42763d6629e44f448aa5d8ae477d61
  10. Affected versionversion=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <9da40aea63f8769f28afb91aea0fac4cf6fbbb65
  11. Affected versionversion=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <bf0de0f9a0544c11f96f93206da04ab87dcea1f4
  12. Affected versionversion=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <ed87190e9d9c80aad220fb6b0b03a84d22e2c95b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.4.22 <5.4.285; version=5.5.6 <5.6; version=5.6; version=6026fd9da213daab95469356fe7fdcf29ae1a296; version=7a97311de48d56af6db4c5819f95faf9b0b23b1a <a71349b692ab34ea197949e13e3cc42570fe73d9; version=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <41fd1e94066a815a7ab0a7025359e9b40e4b3576; version=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <4c98fe0dfa2ae83c4631699695506d8941db4bfe; version=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <65d11eb276836d49003a8060cf31fa2284ad1047; version=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <70b60c8d9b42763d6629e44f448aa5d8ae477d61; version=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <9da40aea63f8769f28afb91aea0fac4cf6fbbb65; version=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <bf0de0f9a0544c11f96f93206da04ab87dcea1f4; version=f4b1363cae43fef7c86c993b7ca7fe7d546b3c68 <ed87190e9d9c80aad220fb6b0b03a84d22e2c95b

Published CVSS scores

7.8Linux CNACVSS: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 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

T1499Endpoint Denial of Service

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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