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Fencer Vulns
high 7.1

CVE-2024-39483 json

KVM: SVM: WARN on vNMI + NMI window iff NMIs are outright masked

published 2024-07-05 2 y ago modified 2026-08-05 3 mo ago also EUVD-2024-38008

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 13%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

KVM: SVM: WARN on vNMI + NMI window iff NMIs are outright masked

When requesting an NMI window, WARN on vNMI support being enabled if and only if NMIs are actually masked, i.e. if the vCPU is already handling an NMI. KVM's ABI for NMIs that arrive simultanesouly (from KVM's point of view) is to inject one NMI and pend the other. When using vNMI, KVM pends the second NMI simply by setting V_NMI_PENDING, and lets the CPU do the rest (hardware automatically sets V_NMI_BLOCKING when an NMI is injected).

However, if KVM can't immediately inject an NMI, e.g. because the vCPU is in an STI shadow or is running with GIF=0, then KVM will request an NMI window and trigger the WARN (but still function correctly).

Whether or not the GIF=0 case makes sense is debatable, as the intent of KVM's behavior is to provide functionality that is as close to real hardware as possible. E.g. if two NMIs are sent in quick succession, the probability of both NMIs arriving in an STI shadow is infinitesimally low on real hardware, but significantly larger in a virtual environment, e.g. if the vCPU is preempted in the STI shadow. For GIF=0, the argument isn't as clear cut, because the window where two NMIs can collide is much larger in bare metal (though still small).

That said, KVM should not have divergent behavior for the GIF=0 case based on whether or not vNMI support is enabled. And KVM has allowed simultaneous NMIs with GIF=0 for over a decade, since commit 7460fb4a3400 ("KVM: Fix simultaneous NMIs"). I.e. KVM's GIF=0 handling shouldn't be modified without a *really* good reason to do so, and if KVM's behavior were to be modified, it should be done irrespective of vNMI support.

Patch / fix

  • Linux Linux 6.6.34, 6.9.5, 6.10
  • linux Debian 14, Debian 13 6.9.7-1

debian advisories DEBIAN-CVE-2024-39483

  • linux Ubuntu 24.04 LTS 6.8.0-44.44
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1015.16
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1014.16
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1010.13
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1012.12
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1014.16
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1011.12
  • linux-riscv Ubuntu 24.04 LTS 6.8.0-44.44.1

ubuntu advisories UBUNTU-CVE-2024-39483

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel RHEL 9 5.14.0-427.40.1.el9_4
  • rv RHEL 9 5.14.0-427.40.1.el9_4
  • perf RHEL 9 5.14.0-427.40.1.el9_4
  • rtla RHEL 9 5.14.0-427.40.1.el9_4
  • bpftool RHEL 9 7.3.0-427.40.1.el9_4
  • libperf RHEL 9 5.14.0-427.40.1.el9_4
  • kernel-rt RHEL 9 5.14.0-427.40.1.el9_4
  • kernel-64k RHEL 9 5.14.0-427.40.1.el9_4

red hat advisories RHSA-2024:8162

  • kernel-rt Linux Micro 6.0 6.4.0-10.1
  • kernel-source-rt Linux Micro 6.0 6.4.0-10.1
  • kernel-livepatch-MICRO-6-0-RT_Update_2 Linux Micro 6.0 1-1.1
  • kernel-source Linux Micro 6.0 6.4.0-19.1
  • kernel-default Linux Micro 6.0 6.4.0-19.1
  • kernel-kvmsmall Linux Micro 6.0 6.4.0-19.1
  • kernel-default-base Linux Micro 6.0 6.4.0-17.1.1.51
  • kernel-livepatch-MICRO-6-0_Update_2 Linux Micro 6.0 1-1.1

suse advisories SUSE-SU-2025:20047-1SUSE-SU-2025:20044-1SUSE-SU-2024:3383-1SUSE-SU-2024:3195-1SUSE-SU-2024:3194-1

  • kernel AlmaLinux 9 5.14.0-427.40.1.el9_4
  • rv AlmaLinux 9 5.14.0-427.40.1.el9_4
  • perf AlmaLinux 9 5.14.0-427.40.1.el9_4
  • rtla AlmaLinux 9 5.14.0-427.40.1.el9_4
  • bpftool AlmaLinux 9 7.3.0-427.40.1.el9_4
  • libperf AlmaLinux 9 5.14.0-427.40.1.el9_4
  • kernel-rt AlmaLinux 9 5.14.0-427.40.1.el9_4
  • kernel-64k AlmaLinux 9 5.14.0-427.40.1.el9_4

almalinux advisories ALSA-2024:8162

  • kernel Rocky Linux 9 5.14.0-427.40.1.el9_4

rocky linux advisories RLSA-2024:8162

  • kernel CBL-Mariner 2.0 5.15.162.2-1

azure linux advisories AZL-43270

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-39483 updated cvss 5.5

kernel: KVM: SVM: WARN on vNMI + NMI window iff NMIs are outright masked

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: no fix available
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-427.40.1.el9_4, perf 5.14.0-427.40.1.el9_4, rtla 5.14.0-427.40.1.el9_4, kernel-devel-matched 5.14.0-427.40.1.el9_4, kernel-64k-devel-matched 5.14.0-427.40.1.el9_4, kernel-debug-devel-matched 5.14.0-427.40.1.el9_4, +6 more Red Hat Enterprise Linux BaseOS (v. 9) bpftool 7.3.0-427.40.1.el9_4, kernel 5.14.0-427.40.1.el9_4, kernel-64k 5.14.0-427.40.1.el9_4, kernel-core 5.14.0-427.40.1.el9_4, kernel-tools 5.14.0-427.40.1.el9_4, python3-perf 5.14.0-427.40.1.el9_4, +28 more Red Hat Enterprise Linux CRB (v. 9) libperf 5.14.0-427.40.1.el9_4, kernel-debuginfo-common-s390x 5.14.0-427.40.1.el9_4, kernel-debuginfo-common-x86_64 5.14.0-427.40.1.el9_4, kernel-debuginfo-common-aarch64 5.14.0-427.40.1.el9_4, kernel-debuginfo-common-ppc64le 5.14.0-427.40.1.el9_4 Red Hat Enterprise Linux NFV (v. 9) kernel-rt 5.14.0-427.40.1.el9_4, kernel-rt-kvm 5.14.0-427.40.1.el9_4, kernel-rt-core 5.14.0-427.40.1.el9_4, kernel-rt-modules 5.14.0-427.40.1.el9_4, kernel-rt-debug-kvm 5.14.0-427.40.1.el9_4, kernel-rt-debug-core 5.14.0-427.40.1.el9_4, +6 more Red Hat Enterprise Linux RT (v. 9) kernel-rt 5.14.0-427.40.1.el9_4, kernel-rt-core 5.14.0-427.40.1.el9_4, kernel-rt-modules 5.14.0-427.40.1.el9_4, kernel-rt-debug-core 5.14.0-427.40.1.el9_4, kernel-rt-modules-core 5.14.0-427.40.1.el9_4, kernel-rt-debug-modules 5.14.0-427.40.1.el9_4, +4 more
    fixed: vendor fix RHSA-2024:8162
  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 13% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD 3.1 5.5 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.