CVE-2026-23789 in Exynos
Summary
by MITRE • 09/14/2026
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.
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Analysis
by VulDB Data Team • 09/14/2026
The identified vulnerability resides within the Media Format Codec or Multi-Format Codec, commonly referred to as MFC, which is a hardware-accelerated video encoding and decoding engine integrated into Samsung Exynos mobile processors including models 850 through 2600 as well as wearable variants W920, W930, and W1000. This component handles critical multimedia processing tasks such as H.264, HEVC, and VP9 encoding and decoding operations. The specific flaw is classified as a double-free vulnerability within the Exynos MFC encoder driver subsystem. A double-free condition occurs when a program attempts to free or release memory that has already been released once before. In this context, the improper cleanup of dma_buf references during error handling paths triggers this condition. DMA buffers are essential for facilitating direct memory access between hardware peripherals and system RAM without continuous CPU intervention. When the driver fails to correctly manage these buffer lifecycles upon encountering an error state, it may invoke a deallocation routine on a pointer that has already been invalidated or freed by another part of the execution flow.
This technical flaw leads directly to kernel memory corruption because the double-free operation disrupts the internal data structures used by the Linux kernel's memory management subsystem, such as slab allocators or buddy systems. These structures rely on accurate tracking of allocated and free blocks to prevent overlaps and ensure system stability. When a block is freed twice, metadata within these structures becomes inconsistent, potentially allowing an attacker who controls input parameters leading to this error path to manipulate heap layout. This manipulation can result in arbitrary code execution with kernel privileges if the corrupted memory region contains function pointers or control flow data that can be overwritten by maliciously crafted inputs. The vulnerability aligns closely with Common Weakness Enumeration identifier CWE-415, which describes double free conditions as a significant class of software defects leading to instability and security breaches.
From an operational perspective, this vulnerability poses severe risks to device integrity and user privacy. Since the MFC driver operates at kernel level, successful exploitation grants attackers full control over the operating system environment. This can lead to complete compromise of confidential data stored on the device, including personal media files, credentials, and encryption keys. Furthermore, it enables persistent malware installation that survives reboots due to its high privilege level. The attack vector typically involves triggering specific video encoding operations with malformed or specially crafted input streams that force the driver into an error state where the improper cleanup routine is executed. This scenario corresponds to ATT&CK technique T1059, Command and Scripting Interpreter, when considering post-exploitation activities enabled by kernel access, and relates to privilege escalation vectors described in MITRE ATT&CK for mobile platforms under local exploitation techniques that bypass security controls through memory corruption flaws.
Mitigation strategies primarily involve patching the Exynos MFC encoder driver to ensure robust reference counting mechanisms are implemented for dma_buf objects. Developers must verify that every allocation has a corresponding and mutually exclusive deallocation path, particularly within error handling branches where control flow diverges from normal execution paths. Implementing static analysis tools during development can help detect potential double-free scenarios before deployment. Additionally, enabling kernel hardening features such as KASLR Kernel Address Space Layout Randomization and SMEP Supervisor Mode Execution Prevention reduces the likelihood of successful exploitation by making it harder for attackers to predict memory addresses or execute code in supervisor mode. Users should apply all available security updates provided by Samsung promptly to mitigate exposure to this vulnerability across affected Exynos processor families.