high 8.8

CVE-2025-37957 json

KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception

published 2025-05-20 17 mo ago modified 2026-10-30 10 d ago also EUVD-2025-15905

cvss: 8.8; 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 8%
public exploits: 0; none known

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

Previously, commit ed129ec9057f ("KVM: x86: forcibly leave nested mode on vCPU reset") addressed an issue where a triple fault occurring in nested mode could lead to use-after-free scenarios. However, the commit did not handle the analogous situation for System Management Mode (SMM).

This omission results in triggering a WARN when KVM forces a vCPU INIT after SHUTDOWN interception while the vCPU is in SMM. This situation was reprodused using Syzkaller by:

1) Creating a KVM VM and vCPU 2) Sending a KVM_SMI ioctl to explicitly enter SMM 3) Executing invalid instructions causing consecutive exceptions and eventually a triple fault

The issue manifests as follows:

WARNING: CPU: 0 PID: 25506 at arch/x86/kvm/x86.c:12112 kvm_vcpu_reset+0x1d2/0x1530 arch/x86/kvm/x86.c:12112 Modules linked in: CPU: 0 PID: 25506 Comm: syz-executor.0 Not tainted 6.1.130-syzkaller-00157-g164fe5dde9b6 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 RIP: 0010:kvm_vcpu_reset+0x1d2/0x1530 arch/x86/kvm/x86.c:12112 Call Trace: <TASK> shutdown_interception+0x66/0xb0 arch/x86/kvm/svm/svm.c:2136 svm_invoke_exit_handler+0x110/0x530 arch/x86/kvm/svm/svm.c:3395 svm_handle_exit+0x424/0x920 arch/x86/kvm/svm/svm.c:3457 vcpu_enter_guest arch/x86/kvm/x86.c:10959 [inline] vcpu_run+0x2c43/0x5a90 arch/x86/kvm/x86.c:11062 kvm_arch_vcpu_ioctl_run+0x50f/0x1cf0 arch/x86/kvm/x86.c:11283 kvm_vcpu_ioctl+0x570/0xf00 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4122 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Architecturally, INIT is blocked when the CPU is in SMM, hence KVM's WARN() in kvm_vcpu_reset() to guard against KVM bugs, e.g. to detect improper emulation of INIT. SHUTDOWN on SVM is a weird edge case where KVM needs to do _something_ sane with the VMCB, since it's technically undefined, and INIT is the least awful choice given KVM's ABI.

So, double down on stuffing INIT on SHUTDOWN, and force the vCPU out of SMM to avoid any weirdness (and the WARN).

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

[sean: massage changelog, make it clear this isn't architectural behavior]

Patch / fix

fixed in 1 distros 3 links 5

Linux Linux 5.16, 6.1, 6.1.191, 6.6.92, 6.12.29, 6.14.7, 6.15

debian ubuntu suse

linux Debian 14, Debian 13 6.12.29-1

debian advisories DEBIAN-CVE-2025-37957

linux Ubuntu 24.04 LTS 6.8.0-100.100
linux-aws Ubuntu 24.04 LTS 6.8.0-1046.49
linux-gcp Ubuntu 24.04 LTS 6.8.0-1047.50
linux-gke Ubuntu 24.04 LTS 6.8.0-1043.48
linux-ibm Ubuntu 24.04 LTS 6.8.0-1044.44
linux-azure Ubuntu 24.04 LTS 6.8.0-1046.52
linux-gkeop Ubuntu 24.04 LTS 6.8.0-1030.33
linux-raspi Ubuntu 24.04 LTS 6.8.0-1047.51

ubuntu advisories UBUNTU-CVE-2025-37957

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

dtb-aarch64 openSUSE Leap 15.6 6.4.0-150600.23.53.1
kernel-64kb SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1
kernel-syms SLE Module for Development Tools 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1
kernel-obs-qa openSUSE Leap 15.6 6.4.0-150600.23.53.1
kernel-source SLE Module for Development Tools 15 SP6, SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1
kernel-default SLE Workstation Extension 15 SP6, SLE Module for Legacy 15 SP6, SLE Module for Basesystem 15 SP6 +3 more 6.4.0-150600.23.53.1
kernel-kvmsmall openSUSE Leap 15.6 6.4.0-150600.23.53.1
kernel-zfcpdump SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 6.4.0-150600.23.53.1

suse advisories SUSE-SU-2025:02000-1 SUSE-SU-2025:01972-1 SUSE-SU-2025:20413-1 SUSE-SU-2025:01967-1 SUSE-SU-2025:01965-1 SUSE-SU-2025:01964-1

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-2025-37957 updated 2026-11-05 cvss 4.4

kernel: KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception

Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
affected: no fix available “Fix deferred”
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 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: total
Assessed: 24 d ago (2026-10-15)

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.8	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
NVD	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Linux Linux

Classification

Weakness

CWE-416 Use After Free

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2025-37957
NVD CVE-2025-37957

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.

Summary