CVE-2024-42240

Kernel warning via premature branch-history clearing

Published Aug 7, 2024 · Updated May 23, 2026

Improper exception handling in Linux allows local users to trigger a kernel warning through a crafted 32-bit SYSENTER call. The x86 entry_SYSENTER_compat path invokes CLEAR_BRANCH_HISTORY before clearing the trap flag, so clear_bhb_loop runs under single-step handling and exc_debug_kernel emits a warning. The trigger requires BHI mitigation, an x86 compatibility path, and local code execution; the invoking process crashes while the kernel records the warning.

CVSS severity5.5
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper exception handling in Linux allows local users to trigger a kernel warning through a crafted 32-bit SYSENTER call. The x86 entry_SYSENTER_compat path invokes CLEAR_BRANCH_HISTORY before clearing the trap flag, so clear_bhb_loop runs under single-step handling and exc_debug_kernel emits a warning. The trigger requires BHI mitigation, an x86 compatibility path, and local code execution; the invoking process crashes while the kernel records the warning.

The record

CVE
CVE-2024-42240
Published
Aug 7, 2024
Updated
May 23, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-835, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 7, 2024CVE publishedPublication date reported by the CVE source.
  2. May 23, 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=07dbb10f153f483e8249acebdffedf922e2ec2e1 <a765679defe1dc1b8fa01928a6ad6361e72a1364
  2. Affected versionversion=5.15.154 <5.15.163
  3. Affected versionversion=6.1.85 <6.1.100
  4. Affected versionversion=6.6.26 <6.6.41
  5. Affected versionversion=6.8.5 <6.9
  6. Affected versionversion=6.9
  7. Affected versionversion=7390db8aea0d64e9deb28b8e1ce716f5020c7ee5 <08518d48e5b744620524f0acd7c26c19bda7f513
  8. Affected versionversion=7390db8aea0d64e9deb28b8e1ce716f5020c7ee5 <ac8b270b61d48fcc61f052097777e3b5e11591e0
  9. Affected versionversion=8f51637712e4da5be410a1666f8aee0d86eef898
  10. Affected versionversion=bd53ec80f21839cfd4d852a6088279d602d67e5b <db56615e96c439e13783d7715330e824b4fd4b84
  11. Affected versionversion=eb36b0dce2138581bc6b5e39d0273cb4c96ded81 <dae3543db8f0cf8ac1a198c3bb4b6e3c24d576cf

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=07dbb10f153f483e8249acebdffedf922e2ec2e1 <a765679defe1dc1b8fa01928a6ad6361e72a1364; version=5.15.154 <5.15.163; version=6.1.85 <6.1.100; version=6.6.26 <6.6.41; version=6.8.5 <6.9; version=6.9; version=7390db8aea0d64e9deb28b8e1ce716f5020c7ee5 <08518d48e5b744620524f0acd7c26c19bda7f513; version=7390db8aea0d64e9deb28b8e1ce716f5020c7ee5 <ac8b270b61d48fcc61f052097777e3b5e11591e0; version=8f51637712e4da5be410a1666f8aee0d86eef898; version=bd53ec80f21839cfd4d852a6088279d602d67e5b <db56615e96c439e13783d7715330e824b4fd4b84; version=eb36b0dce2138581bc6b5e39d0273cb4c96ded81 <dae3543db8f0cf8ac1a198c3bb4b6e3c24d576cf

Published CVSS scores

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-835Loop with Unreachable Exit Condition ('Infinite Loop')
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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