CVE-2024-42126: powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt.
Vulnerability summary
CVE-2024-42126 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.23% chance of exploitation in the next 30 days, higher than 13.7% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 28 · Related 25Timeline
- 30-07-2024PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.23%
Chance of exploitation in the next 30 days
Percentile
14%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.23% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu130 products
- linuxAll versions (No fix recorded) | < 5.15.0-125.135 | < 6.8.0-48.48
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.15.0-1072.78 | < 6.8.0-1018.20
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ eb553f16973ade990d05946af9ae191394712c8a, < fb6675db04c4b79883373edc578d5df7bbc84848 | ≥ eb553f16973ade990d05946af9ae191394712c8a, < e2afb26615adf6c3ceaaa7732aa839bcd587a057 | ≥ eb553f16973ade990d05946af9ae191394712c8a, < 8d3f83dfb23674540c827a8d65fba20aa300b252 | ≥ eb553f16973ade990d05946af9ae191394712c8a, < 0f37946c62c48a907625348cbc720a7a0c547d1e | ≥ eb553f16973ade990d05946af9ae191394712c8a, < 2c78c9411e685dbc9eac8c2845111b03501975b8 | ≥ eb553f16973ade990d05946af9ae191394712c8a, < 0db880fc865ffb522141ced4bfa66c12ab1fbb70 | 5.10
- linux_kernel≥ 5.10, < 5.10.224 | ≥ 5.11, < 5.15.165 | ≥ 5.16, < 6.1.98 | ≥ 6.2, < 6.6.39 | ≥ 6.7, < 6.9.9
Debian1 product
- linux< 6.1.98-1 | < 6.9.9-1
3 vendors · 133 products
