CVE-2024-42240: Linux kernel · x86/bhi: Avoid warning in #DB handler due to BHI mitigation
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 4.4.0-1138.144 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 23:28 UTC
- Patch
- Available – fixed in 4.4.0-1138.144, 4.15.0-1183.198~14.04.1, 4.4.0-261.295~14.04.1 +98
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 7 Aug 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Patches and advisories
- ubuntu.com/security/notices/USN-7007-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7009-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7019-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7009-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7090-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7095-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-4 (opens in a new tab)
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 24.04 LTSlinux-gkeoppkg:deb/ubuntu/linux-gkeop?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In the Linux kernel, the following vulnerability has been resolved: x86/bhi: Avoid warning in #DB handler due to BHI mitigation When BHI mitigation is enabled, if SYSENTER is invoked with the TF flag set then entry_SYSENTER_compat() uses CLEAR_BRANCH_HISTORY and calls the clear_bhb_loop() before the TF flag is cleared. This causes the #DB handler (exc_debug_kernel()) to issue a warning because single-step is used outside the entry_SYSENTER_compat() function. To address this issue, entry_SYSENTER_compat() should use CLEAR_BRANCH_HISTORY after making sure the TF flag is cleared. The problem can be reproduced with the following sequence: $ cat sysenter_step.c int main() { asm("pushf; pop %ax; bts $8,%ax; push %ax; popf; sysenter"); } $ gcc -o sysenter_step sysenter_step.c $ ./sysenter_step Segmentation fault (core dumped) The program is expected to crash, and the #DB handler will issue a warning. Kernel log: WARNING: CPU: 27 PID: 7000 at arch/x86/kernel/traps.c:1009 exc_debug_kernel+0xd2/0x160 ... RIP: 0010:exc_debug_kernel+0xd2/0x160 ... Call Trace: <#DB> ? show_regs+0x68/0x80 ? __warn+0x8c/0x140 ? exc_debug_kernel+0xd2/0x160 ? report_bug+0x175/0x1a0 ? handle_bug+0x44/0x90 ? exc_invalid_op+0x1c/0x70 ? asm_exc_invalid_op+0x1f/0x30 ? exc_debug_kernel+0xd2/0x160 exc_debug+0x43/0x50 asm_exc_debug+0x1e/0x40 RIP: 0010:clear_bhb_loop+0x0/0xb0 ... </#DB> <TASK> ? entry_SYSENTER_compat_after_hwframe+0x6e/0x8d </TASK> [ bp: Massage commit message. ]
References
- ubuntu.com/security/CVE-2024-42240 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2024-42240 (opens in a new tab)
- git.kernel.org/linus/ac8b270b61d48fcc61f052097777e3b5e11591e0 (opens in a new tab)
- git.kernel.org/stable/c/db56615e96c439e13783d7715330e824b4fd4b84 (opens in a new tab)
- git.kernel.org/stable/c/a765679defe1dc1b8fa01928a6ad6361e72a1364 (opens in a new tab)
- git.kernel.org/stable/c/dae3543db8f0cf8ac1a198c3bb4b6e3c24d576cf (opens in a new tab)
- git.kernel.org/stable/c/08518d48e5b744620524f0acd7c26c19bda7f513 (opens in a new tab)
- git.kernel.org/stable/c/ac8b270b61d48fcc61f052097777e3b5e11591e0 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7009-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7019-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7007-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7009-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7090-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-7095-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-4 (opens in a new tab)