CVE-2026-89910 in Linux
Summary
by MITRE • 09/17/2026
In the Linux kernel, the following vulnerability has been resolved:
LoongArch: KVM: Fix uninitialized stack variable issue with dmsintc
Variable vector[] is declared on stack in function dmsintc_inject_irq()
and sometimes it is used without initialized. Here fix this issue.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 09/17/2026
The Linux kernel vulnerability identified as CVE-2024-related involves an uninitialized stack variable within the LoongArch architecture-specific KVM implementation, specifically affecting the dmsintc interrupt controller emulation logic. The core technical flaw resides in the function dmsintc_inject_irq(), where a local array named vector is declared on the call stack but fails to be fully initialized before being utilized during interrupt injection operations. In C programming, variables allocated on the stack retain whatever data previously existed at that memory location unless explicitly zeroed or assigned by the developer. When this uninitialized vector array is accessed later in the execution flow, it introduces non-deterministic behavior because the contents of the array depend entirely on prior usage of that specific stack frame by other functions or system processes. This lack of initialization violates fundamental principles of secure coding and memory safety within kernel-space operations, where predictable state transitions are critical for maintaining system integrity.
From a security architecture perspective, this flaw aligns with CWE-457, which describes the use of an uninitialized variable. In the context of virtualization, such vulnerabilities can lead to severe operational impacts including information disclosure or privilege escalation. If the uninitialized memory contains sensitive data from previous kernel operations, it could potentially be leaked to a guest operating system through the emulated interrupt controller interface. Furthermore, if the garbage values influence control flow decisions within the KVM subsystem, an attacker with access to the virtual machine might exploit this unpredictability to crash the host or escape the VM sandbox. The ATT&CK framework categorizes such issues under techniques related to exploitation of binary vulnerabilities and potentially privilege escalation via kernel exploits, highlighting the risk that uninitialized memory states pose in complex systems like hypervisors where isolation boundaries must be strictly enforced.
The operational impact extends beyond immediate security breaches to include system stability concerns. Uninitialized variables can cause subtle bugs that manifest as intermittent crashes or data corruption within the virtualized environment. Since KVM manages hardware resources and interrupt routing for guest VMs, any inconsistency in how interrupts are injected due to corrupted vector states could lead to missed interrupts, delayed responses, or incorrect handling of device emulation requests. This degrades performance reliability and may trigger kernel panics on the host machine if error handling paths fail to account for such anomalous inputs. For enterprise deployments relying on LoongArch-based servers running multiple virtual machines, this represents a significant risk vector that undermines the trustworthiness of the underlying infrastructure layer.
Mitigation strategies primarily involve applying the upstream Linux kernel patch that resolves this issue by ensuring proper initialization of the vector array before its first use. Developers should enforce strict coding standards requiring explicit zeroing or assignment of all stack-allocated structures prior to access, particularly in performance-critical paths like interrupt handling where optimization might tempt developers to skip initialization steps assuming clean state. Static analysis tools and compiler warnings such as -Wuninitialized can help detect these issues early in the development lifecycle. Additionally, runtime hardening mechanisms like KASAN (Kernel Address Sanitizer) are valuable for detecting out-of-bounds accesses or use of uninitialized memory during testing phases before deployment to production environments. Regular updates to the kernel package on LoongArch systems remain essential to maintain a secure posture against such low-level implementation flaws.