CVE-2026-23786 in Exynos
Summary
by MITRE • 09/14/2026
An issue was discovered in DPU in Samsung Mobile Processor Exynos 1280, 2200, 1380, 1480, 2400, 1580, 2500, 1680, and 2600. A TOCTOU race condition in the Exynos DRM HDR Driver leads to a heap overflow, causing a kernel crash.
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Analysis
by VulDB Data Team • 09/14/2026
The vulnerability identified within Samsung Mobile Processors including the Exynos series such as models 1280 through 2600 centers on a critical flaw located in the Display Processing Unit subsystem managed by the DRM HDR Driver. This component is responsible for handling high dynamic range video processing and display output, which requires precise synchronization between user-space applications requesting specific rendering parameters and kernel-space drivers managing hardware resources. The core technical issue stems from a Time of Check to Time of Use race condition that arises during this interaction. In this scenario, the driver performs an initial validation or allocation check on data structures provided by a potentially unprivileged process but fails to maintain strict atomicity over the subsequent usage phase. Between the moment the validity is verified and the moment the memory is actually accessed or utilized for rendering operations, another thread of execution can modify the underlying state or input parameters. This temporal gap allows an attacker to manipulate the data in flight, effectively bypassing the initial security checks that were designed to prevent buffer overflows.
The exploitation of this race condition directly results in a heap overflow within the kernel memory space. Because the driver allocates buffers based on validated sizes but processes them using potentially altered dimensions due to the concurrent modification allowed by the TOCTOU flaw, it writes data beyond the boundaries of the allocated heap region. This out-of-bounds write corrupts adjacent memory structures, including metadata used for memory management and potentially other kernel objects. The immediate operational impact is a system instability that manifests as a kernel panic or crash, leading to a denial of service condition where the device becomes unresponsive and requires a reboot. However, beyond simple availability disruption, heap overflows in kernel space are particularly dangerous because they can be leveraged for arbitrary code execution if an attacker carefully crafts the overflow payload to overwrite function pointers or return addresses within the kernel memory layout. This transforms what appears as a stability issue into a severe privilege escalation vector, allowing local attackers with access to display interfaces to gain root-level control over the operating system.
From a classification perspective, this vulnerability aligns closely with CWE-362 which defines concurrent execution using shared resources with improper synchronization leading to race conditions. The specific mechanism of checking validity before use without maintaining atomicity is a classic example of this category. Furthermore, in terms of attack tactics and techniques as defined by the MITRE ATT&CK framework for mobile platforms, this flaw facilitates privilege escalation through local exploitation paths that target kernel memory corruption. It also relates to CWE-120 which covers buffer copy operations without checking size limits, although the root cause here is the race condition rather than a simple lack of bounds check in a single-threaded context. The presence of such flaws in mobile SoCs highlights the complexity of securing hardware-accelerated subsystems where performance optimizations often prioritize speed over rigorous synchronization primitives.
Mitigation strategies for this vulnerability require both immediate software patches and long-term architectural improvements. Samsung has addressed this issue by updating the DRM HDR Driver to enforce stricter locking mechanisms that ensure atomicity between validation and usage phases, thereby eliminating the window of opportunity for race condition exploitation. Developers integrating these processors into their devices must apply the latest security updates provided by SoC vendors promptly. For system architects, it is advisable to implement defense-in-depth measures such as Kernel Address Space Layout Randomization which makes exploiting heap overflows significantly more difficult by randomizing memory addresses. Additionally enabling hardware-based isolation features like TrustZone can help contain potential breaches within secure enclaves rather than allowing them to compromise the main operating system kernel. Continuous monitoring of display subsystem logs and implementing strict access controls for applications that interact with DRM interfaces further reduces the attack surface available to local adversaries seeking to trigger these race conditions.