CVE-2026-11891 in Valhall GPU Userspace Driver
Summary
by MITRE • 09/08/2026
Use After Free vulnerability in Arm Ltd Valhall GPU Userspace Driver, Arm Ltd Arm 5th Gen GPU Architecture Userspace Driver allows a non-privileged user process to perform valid GPU processing operations, including via WebGL or WebGPU, to access already freed memory.
This issue affects Valhall GPU Userspace Driver: from r46p0 through r49p5, from r50p0 through r54p3, r55p0; Arm 5th Gen GPU Architecture Userspace Driver: from r46p0 through r49p5, from r50p0 through r54p3, r55p0.
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Analysis
by VulDB Data Team • 09/08/2026
The identified vulnerability represents a critical memory safety flaw within the userspace driver components for Arm Ltd's Valhall GPU and 5th Generation ARM GPU Architecture. This issue is classified as an Use After Free condition, which occurs when software continues to use a pointer after it has been freed from its allocated memory block. In this specific context, the vulnerability resides in the handling of graphics processing operations managed by the userspace driver, specifically affecting versions ranging from r46p0 through r54p3 and including release r55p0 for both architectural variants. The core technical failure involves a race condition or logic error where memory buffers allocated for GPU rendering tasks are deallocated prematurely while still being referenced by active processing queues or command streams initiated by user applications.
From an operational perspective, this flaw allows any non-privileged user process to exploit the vulnerability through standard graphics APIs such as WebGL or WebGPU. These interfaces provide a common pathway for web-based and native applications to offload rendering tasks to the GPU hardware via the driver stack. When an application submits commands that trigger the premature freeing of memory buffers while those buffers are still referenced by pending GPU operations, the processor may attempt to read from or write to the now-invalid memory address. This behavior violates fundamental principles of memory isolation and integrity, creating a pathway for unauthorized data access and potential code execution within the context of the compromised process or potentially escalating privileges depending on the driver's implementation details and kernel interactions.
The security implications are severe due to the nature of GPU drivers operating with elevated system permissions relative to standard user applications. An attacker leveraging this Use After Free vulnerability can achieve arbitrary read-write primitives, which facilitates information disclosure by leaking sensitive data from adjacent memory regions or enabling remote code execution if specific heap grooming techniques are employed to control the contents of the freed memory block before it is reallocated for malicious purposes. This aligns with Common Weakness Enumeration identifier CWE-416, which describes the danger of using a pointer after its associated memory has been released. The attack vector typically involves crafting malformed WebGL or WebGPU command sequences that trigger the specific timing window where the driver fails to synchronize buffer lifecycle management correctly.
In terms of threat modeling and industry standards, this vulnerability maps directly to MITRE ATT&CK technique T1203, which covers Exploitation for Client Execution, as attackers often utilize legitimate software features like graphics APIs to deliver exploits without triggering security alerts associated with traditional malware delivery methods. Furthermore, the ability to access freed memory can lead to CWE-787, Out-of-bounds Write, if the attacker controls the data written into the reused buffer location. The impact extends beyond simple application crashes; it compromises the confidentiality and integrity of the host system by allowing a low-privilege process to interact with kernel-mode driver structures or other protected memory spaces through improper pointer dereferencing.
Mitigation strategies primarily involve applying vendor-provided patches that address the synchronization logic within the userspace driver codebase. System administrators should ensure that all affected versions, specifically those from r46p0 through r54p3 and release r55p0 for both Valhall and 5th Gen ARM GPU architectures, are updated to secure revisions where memory lifecycle management is strictly enforced. Developers utilizing WebGL or WebGPU on devices powered by these GPUs should monitor for driver updates provided by device manufacturers who integrate the Arm graphics stack into their operating systems. Additionally, implementing runtime protection mechanisms such as Address Space Layout Randomization and hardware-enforced isolation features can help mitigate the impact of exploitation attempts until definitive patches are deployed across all affected endpoints.