Critical Vulnerability in Linux Kernel: KVM Access to Uninitialized vCPU Events
Summary
DEBIAN-CVE-2025-40102: In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Prevent access to vCPU events before init Another day, another syzkaller bug. Affects linux versions 5.10.103-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is the core component of many operating systems, providing essential services for hardware and software interaction. It is known for its stability, performance, and security features. However, vulnerabilities can arise, affecting its functionality and security. This specific vulnerability pertains to the Kernel-based Virtual Machine (KVM) subsystem, which allows multiple virtual machines to run on a single physical host. The flaw allows userspace to pend vCPU events for uninitialized vCPUs, potentially leading to system instability and security risks.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the KVM subsystem for arm64 architecture. This flaw allows userspace to pend vCPU events for a vCPU that has not been initialized, leading to the kernel interpreting uninitialized data. This can cause the system to enter an illegal state, resulting in a kernel panic and potential data loss. The vulnerability was introduced due to improper checks in the KVM code, allowing for erroneous behavior during exception handling. The specific error occurs in the exception_target_el function, where a bug is triggered if the vCPU's state is not properly initialized.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
Currently, there are no specific workarounds mentioned for this vulnerability. The best course of action is to apply the patch by updating the kernel as described in the 'how_to_fix' section.
Conclusion
The vulnerability in the Linux kernel related to KVM access to uninitialized vCPU events poses significant risks to system stability and security. Users are strongly encouraged to update their kernel to the latest patched version to mitigate these risks. Regular monitoring for vulnerabilities using tools like Vulert can help maintain the security of your systems.
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FAQ
The vulnerability can lead to system instability, kernel panics, and potential data loss due to the improper handling of uninitialized vCPU events.
You can use the Vulert platform to monitor and alert for open-source vulnerabilities in your software. Visit Vulert Scanner to check if your application is affected by this vulnerability.
Yes, a patch is available in the latest versions of the Linux kernel. Users are advised to update their kernel to the latest version to mitigate the risk.
While there are no specific workarounds, it is crucial to prioritize updating your kernel as soon as possible to avoid potential risks associated with this vulnerability.
Detailed information about this vulnerability can be found in the official CVE database and through security advisories related to the Linux kernel.
References
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