Critical Vulnerability in Linux Kernel: KVM SMM Mode Handling Issue
Summary
DEBIAN-CVE-2025-37957: 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") addres... Affects linux versions < 6.12.29-1. Fixed in 6.12.29-1. How to fix ↓
Check if this vulnerability affects your application
Upload a manifest or SBOM and we'll show whether you're affected, plus every other risky package in the same scan.
No signup required · Results in about 60 seconds
Habilume
Habit tracker with a companion that grows with you
Complete habits, earn Lume Points, and watch your Lume grow as you stay consistent.
Background
The Linux kernel is the core component of many operating systems, providing essential services for hardware management, process scheduling, and system security. It supports a wide range of hardware architectures and is known for its robustness and flexibility. However, vulnerabilities can arise, impacting system stability and security. This particular vulnerability affects the KVM (Kernel-based Virtual Machine) subsystem, specifically in how it handles System Management Mode (SMM) during shutdown interceptions.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the KVM subsystem related to the handling of System Management Mode (SMM) during shutdown interceptions. The issue stems from a previous commit that addressed a similar problem in nested mode but overlooked the SMM scenario. When a KVM virtual CPU (vCPU) is forced to leave SMM during a shutdown interception, it can trigger a warning (WARN) in the kernel, indicating a potential use-after-free scenario. This can lead to system instability and unexpected behavior, particularly when invalid instructions are executed, resulting in consecutive exceptions and a triple fault.
How To Fix
Minimum fixed version
6.12.29-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade linuxTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
Currently, there are no specific workarounds mentioned for this vulnerability. It is recommended to apply the patch as soon as it is available to mitigate any risks associated with this issue.
Conclusion
The vulnerability in the Linux kernel's KVM subsystem regarding SMM mode handling during shutdown interceptions poses significant risks to system stability and security. Users are urged to update their kernels to the patched version to mitigate these risks. Monitoring tools like Vulert can assist in identifying vulnerabilities in real-time.
See every vulnerability recorded for linux →
FAQ
The vulnerability can lead to system instability and unexpected behavior when a KVM vCPU is forced to leave SMM during shutdown interceptions.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time. Visit Vulert Scanner to check if your application is affected without needing to sign up.
While there are no specific workarounds, it is crucial to plan for an update as soon as possible to mitigate risks.
This vulnerability is similar to a previous issue addressed in nested mode but specifically pertains to the handling of SMM, which was not covered in that fix.
Detailed information about this vulnerability can be found in the Debian CVE database at https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-37957.json.
References
Related vulnerabilities
Recent vulnerabilities recorded for linux.
Habilume
Habit tracker with a companion that grows with you
Complete habits, earn Lume Points, and watch your Lume grow as you stay consistent.
