# CVE-2025-37957: KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception

> A use-after-free vulnerability in the Linux kernel's KVM SVM module allows a local attacker to cause a denial of service or potentially execute code via a triple fault in SMM.

- **Severity:** High 8.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 20 May 2025
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-70259, BELL-CVE-2025-37957, DEBIAN-CVE-2025-37957, GHSA-5vj7-r55g-9xv7, ROOT-OS-DEBIAN-12-CVE-2025-37957, ROOT-OS-UBUNTU-2204-CVE-2025-37957, ROOT-OS-UBUNTU-2404-CVE-2025-37957, UBUNTU-CVE-2025-37957

## What is CVE-2025-37957?

CVE-2025-37957 is a high-severity use after free vulnerability in Linux kernel, published on 20 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception

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]

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2025-37957?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-37957?

Apply the vendor's patch.

## Is CVE-2025-37957 being exploited?

There is no known exploitation of CVE-2025-37957 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-37957 and fix it if it is affected.

What it is: CVE-2025-37957 is a high-severity use after free vulnerability in Linux kernel, published on 20 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-37957 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-37957/ (Markdown: https://insights.sbomify.com/CVE-2025-37957/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-37957
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-37957
- OSV: https://osv.dev/vulnerability/CVE-2025-37957

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-37957/
Summaries are generated and may contain mistakes; the official description above is the record.