Description

In the Linux kernel, the following vulnerability has been resolved: ACPICA: validate handler object type in two places ACPICA: validate handler object type in acpi_ev_has_default_handler() and acpi_ev_find_region_handler().

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.4",
  "pubDate": "2026-09-24T17:17:23.350Z",
  "pubdate": "2026-09-24T17:17:23.350Z",
  "executiveSummary": "The Linux kernel's ACPICA (ACPI Component Architecture) subsystem contains a vulnerability stemming from insufficient validation of handler object types. This flaw, located within specific event handling functions, allows for improper object type handling, potentially leading to memory corruption or undefined kernel behavior.\nThe vulnerability type is categorized as improper input validation, specifically failing to verify that an expected object type matches the actual type at runtime. This poses a significant security risk, as it may be leveraged to achieve kernel-level code execution or cause a denial-of-service (DoS) condition.\nAffected systems include any Linux kernel version utilizing the impacted ACPICA code. Successful exploitation typically requires an attacker to have local access or the ability to manipulate ACPI tables, thereby influencing the kernel's interaction with hardware abstraction layer handlers.\nThe impact includes potential privilege escalation if an attacker can control the execution flow via corrupted object pointers. Mitigation requires applying the official kernel patches that enforce strict type checking for handlers within the ACPICA subsystem.",
  "technicalDetails": "The vulnerability resides within the ACPI Component Architecture (ACPICA) framework, specifically affecting the functions acpi_ev_has_default_handler() and acpi_ev_find_region_handler(). These functions are responsible for managing and locating ACPI operation region handlers, which process requests for hardware interactions defined in ACPI tables.\nThe root cause is a failure in the kernel to perform rigorous object type verification before proceeding with handler operations. In the original implementation, these functions assumed that the object returned from the internal object store was of the expected type without validating the ACPI object descriptor type field. This type confusion allows an attacker—capable of injecting or modifying ACPI tables (e.g., via firmware manipulation or specific kernel interfaces)—to substitute an arbitrary object type for a legitimate handler object.\nThe exploitation flow begins with the manipulation of ACPI tables to reference a malicious or unexpected object in place of a standard operation region handler. When the kernel traverses these structures, the vulnerable functions acpi_ev_has_default_handler() or acpi_ev_find_region_handler() are invoked. Because they lack explicit checks for the handler object type, they interpret the crafted object's data as a valid handler structure.\nThis leads to an invalid memory access or a control-flow redirection, where the kernel treats attacker-controlled data as function pointers or struct members. By carefully crafting this payload, an attacker could achieve arbitrary kernel memory writes or redirect execution flow to attacker-controlled code, effectively bypassing kernel protections. The impact is critical, as these operations occur within the kernel context, providing the attacker with elevated privileges.\nThe vulnerability does not require authentication in the traditional sense, but it is heavily dependent on the attacker's ability to interface with the ACPI subsystem, usually requiring high-level local access or the ability to modify ACPI firmware structures, which the OS subsequently parses. The fix involves adding explicit type validation checks using the ACPICA internal APIs to ensure the retrieved object is indeed a handler object before attempting to interact with it, thereby preventing the type confusion vulnerability."
}