CVE-2024-42126: Linux kernel · powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 5.15.0-1072.78~20.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 23:28 UTC
- Patch
- Available – fixed in 5.15.0-1072.78~20.04.1, 5.15.0-1078.87~20.04.1, 5.15.0-1071.79~20.04.1 +54
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 30 Jul 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-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-7100-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7100-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-6 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-7 (opens in a new tab)
- ubuntu.com/security/notices/USN-7123-1 (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: powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt. nmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel crash when invoked during real mode interrupt handling (e.g. early HMI/MCE interrupt handler) if percpu allocation comes from vmalloc area. Early HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI() wrapper which invokes nmi_enter/nmi_exit calls. We don't see any issue when percpu allocation is from the embedded first chunk. However with CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu allocation can come from the vmalloc area. With kernel command line "percpu_alloc=page" we can force percpu allocation to come from vmalloc area and can see kernel crash in machine_check_early: [ 1.215714] NIP [c000000000e49eb4] rcu_nmi_enter+0x24/0x110 [ 1.215717] LR [c0000000000461a0] machine_check_early+0xf0/0x2c0 [ 1.215719] --- interrupt: 200 [ 1.215720] [c000000fffd73180] [0000000000000000] 0x0 (unreliable) [ 1.215722] [c000000fffd731b0] [0000000000000000] 0x0 [ 1.215724] [c000000fffd73210] [c000000000008364] machine_check_early_common+0x134/0x1f8 Fix this by avoiding use of nmi_enter()/nmi_exit() in real mode if percpu first chunk is not embedded.
References
- ubuntu.com/security/CVE-2024-42126 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2024-42126 (opens in a new tab)
- git.kernel.org/linus/0db880fc865ffb522141ced4bfa66c12ab1fbb70 (opens in a new tab)
- git.kernel.org/stable/c/8d3f83dfb23674540c827a8d65fba20aa300b252 (opens in a new tab)
- git.kernel.org/stable/c/0f37946c62c48a907625348cbc720a7a0c547d1e (opens in a new tab)
- git.kernel.org/stable/c/2c78c9411e685dbc9eac8c2845111b03501975b8 (opens in a new tab)
- git.kernel.org/stable/c/0db880fc865ffb522141ced4bfa66c12ab1fbb70 (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-7100-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7100-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-5 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-6 (opens in a new tab)
- ubuntu.com/security/notices/USN-7089-7 (opens in a new tab)
- ubuntu.com/security/notices/USN-7123-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-7144-1 (opens in a new tab)