Description

An issue was discovered in MFC in Samsung Mobile Processor and Wearable Processor Exynos 850, 1080, 2100, 1280, 2200, 1330, 1380, 1480, 2400, 1580, 2500, 2600, 1680, W920, W930, and W1000. A double-free vulnerability in the Exynos MFC encoder driver (due to improper cleanup of dma_buf references during error handling) leads to kernel memory corruption and potential arbitrary code execution.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.8",
  "pubDate": "2026-09-14T02:17:13.397Z",
  "pubdate": "2026-09-14T02:17:13.397Z",
  "executiveSummary": "A critical double-free vulnerability exists within the Samsung Exynos Multi-Function Codec (MFC) encoder driver, affecting various Mobile and Wearable Processors including the 850, 1080, 2100, 1280, 2200, 1330, 1380, 1480, 2400, 1580, 2500, 2600, 1680, W920, W930, and W1000.\nThe vulnerability stems from improper cleanup logic involving dma_buf references during error handling routines within the kernel-space encoder driver.\nSuccessful exploitation of this flaw leads to kernel memory corruption, which can be leveraged by a local attacker to achieve arbitrary code execution with kernel-level privileges.\nThe risk implication is severe, as memory corruption in a privileged driver context typically results in full system compromise.\nExploitation requires an attacker to possess the ability to interact with the MFC driver, typically through a malicious application with standard user-level permissions on the device.\nDue to the nature of kernel-space corruption, this vulnerability allows for bypasses of standard security mitigations, potentially leading to unauthorized data access, persistence, or denial of service.",
  "technicalDetails": "The vulnerability is located in the MFC encoder driver of the Exynos kernel subsystem. It is classified as a double-free memory management defect triggered during the execution of specific error handling code paths.\nRoot cause analysis indicates a failure in the reference counting or lifecycle management of dma_buf objects. When an error occurs during the encoder initialization or operation phase, the driver's cleanup routine is invoked to release allocated resources. Due to logic errors in the error handling path, the driver may attempt to release or decrement the reference count of a dma_buf pointer twice or perform redundant cleanup operations on an already freed memory structure.\nThe attack flow commences with a local user application initiating specific IOCTL commands to the MFC driver that are designed to trigger an error state. By intentionally inducing this error under carefully managed heap conditions, an attacker influences the driver's cleanup execution path.\nWhen the double-free occurs, the kernel memory allocator (e.g., SLUB/SLAB allocator) marks the memory block as free twice. This corrupts the allocator's internal tracking metadata, such as the freelist pointers. A subsequent allocation request allows the attacker to receive a pointer to memory that is still perceived as being in use by other kernel subsystems.\nBy overlapping controlled data with critical kernel objects, an attacker can overwrite function pointers, kernel stack data, or object structures. This provides the primitives necessary to redirect execution flow to attacker-supplied shellcode or existing kernel ROP gadgets.\nThe exploitation process typically involves grooming the kernel heap to ensure the freed slot is immediately occupied by an attacker-controlled object. Successful exploitation grants the attacker arbitrary code execution within the kernel context (EL1). Given the elevated privilege level, the attacker can disable security features, escalate privileges for their process, or exfiltrate sensitive data directly from kernel memory.\nThis vulnerability is confined to the local execution environment, requiring an attacker to be authenticated as a local user on the system to interact with the device nodes associated with the MFC driver. No network exposure is inherent to the driver's functionality, though it remains a high-severity target for local privilege escalation chains."
}