CVE-2026-97455 in Linux
Summary
by MITRE • 09/24/2026
In the Linux kernel, the following vulnerability has been resolved:
ACPICA: Fix use-after-free in acpi_ds_terminate_control_method()
Fix use-after-free issue in acpi_ds_terminate_control_method() by clearing references to method locals and arguments.
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Analysis
by VulDB Data Team • 09/24/2026
The resolution of a use-after-free vulnerability within the Advanced Configuration and Power Interface (ACPI) Component Architecture (ACPICA) subsystem addresses a critical memory safety flaw located in the acpi_ds_terminate_control_method function. This specific issue arises during the lifecycle management of ACPI control methods, which are scripts executed by the operating system to manage hardware configuration, power states, and thermal policies. When an ACPI method terminates, whether through normal completion or abrupt interruption due to errors such as timeouts or exceptions, the kernel must properly clean up associated resources. The vulnerability stemmed from a failure to explicitly clear references held in local variables and argument slots before releasing the memory structures that contained them. This oversight meant that subsequent operations attempting to access these data structures could interact with freed memory regions, leading to undefined behavior that attackers can exploit for arbitrary code execution or system crashes.
From a technical perspective, this flaw is classified under CWE-416, which denotes Use After Free vulnerabilities in software development. The root cause lies in the improper sequencing of resource deallocation and reference invalidation within the ACPI interpreter's state management logic. In complex systems where multiple threads may interact with hardware states or where asynchronous events trigger method terminations, retaining dangling pointers creates a race condition window. An attacker who can influence the execution flow of an ACPI method—potentially through malicious firmware tables injected via physical access or compromised peripheral devices—could manipulate the timing of memory deallocation to ensure that their controlled data is allocated in the same memory location previously occupied by the freed structure. This technique, often referred to as heap spraying or object reuse, allows for precise control over what values are read from the stale pointer, facilitating privilege escalation or denial of service attacks against the kernel space.
The operational impact of this vulnerability extends beyond simple application crashes. Because ACPI methods operate at a high level within the operating system's hardware abstraction layer, successful exploitation can lead to full kernel compromise. This grants an attacker unrestricted access to all system resources, including sensitive data stored in memory, cryptographic keys, and user credentials. Furthermore, even if code execution is not achieved, the instability introduced by accessing freed memory can cause unpredictable system behavior, leading to frequent kernel panics or blue screens that disrupt critical services. In virtualized environments or cloud infrastructure, this could potentially allow a guest OS to escape isolation boundaries if ACPI tables are shared or improperly isolated between guests and the hypervisor, although such scenarios depend heavily on specific hardware implementations and security configurations.
Mitigation strategies primarily involve applying the provided kernel patch which ensures that all references to method locals and arguments are explicitly cleared upon termination of the control method. This practice aligns with secure coding standards recommended by organizations like OWASP and CERT/CC for managing dynamic memory in C-based systems. Administrators should ensure their Linux distributions receive timely updates, as this fix is typically backported into stable kernel releases. Additionally, hardening measures such as enabling Kernel Address Sanitizer (KASAN) during development or testing phases can help detect similar issues early by tracking invalid memory accesses. For production environments where immediate patching is not feasible due to stability concerns, restricting physical access to systems and auditing ACPI table sources from trusted vendors reduces the attack surface available for injecting malicious control methods that trigger this code path.