CVE-2024-42239

System hang via mutually cancelling BPF timers

Published Aug 7, 2024 · Updated May 11, 2026

Improper locking in affected Linux kernel releases allows local users to hang the system via mutually cancelling BPF timer callbacks. Parallel callbacks can each call bpf_timer_cancel on the other's timer, causing both synchronous cancellations to wait indefinitely for the other callback. Reaching the flaw requires permission to execute BPF timer callbacks and the parallel cancellation schedule; the documented consequence is a kernel lockup.

CVSS severity5.5
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper locking in affected Linux kernel releases allows local users to hang the system via mutually cancelling BPF timer callbacks. Parallel callbacks can each call bpf_timer_cancel on the other's timer, causing both synchronous cancellations to wait indefinitely for the other callback. Reaching the flaw requires permission to execute BPF timer callbacks and the parallel cancellation schedule; the documented consequence is a kernel lockup.

The record

CVE
CVE-2024-42239
Published
Aug 7, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-667, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 7, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 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=5.15
  2. Affected versionversion=b00628b1c7d595ae5b544e059c27b1f5828314b4 <3e4e8178a8666c56813bd167b848fca0f4c9af0a
  3. Affected versionversion=b00628b1c7d595ae5b544e059c27b1f5828314b4 <9369830518688ecd5b08ffc08ab3302ce2b5d0f7
  4. Affected versionversion=b00628b1c7d595ae5b544e059c27b1f5828314b4 <d4523831f07a267a943f0dde844bf8ead7495f13

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.15; version=b00628b1c7d595ae5b544e059c27b1f5828314b4 <3e4e8178a8666c56813bd167b848fca0f4c9af0a; version=b00628b1c7d595ae5b544e059c27b1f5828314b4 <9369830518688ecd5b08ffc08ab3302ce2b5d0f7; version=b00628b1c7d595ae5b544e059c27b1f5828314b4 <d4523831f07a267a943f0dde844bf8ead7495f13

Published CVSS scores

5.5NISTCVSS: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-667Improper Locking
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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