CVE-2026-68446 in Linux
Summary
by MITRE • 08/12/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/vmwgfx: Validate vmw_surface_metadata::array_size
This field comes from userspace and should be validated against specific limits depending on which Shader Model (SM) is available.
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Analysis
by VulDB Data Team • 08/12/2026
The vulnerability in question resides within the VMware graphics driver component of the Linux kernel, specifically affecting the drm/vmwgfx subsystem responsible for managing virtualized graphics resources. This issue pertains to insufficient validation of user-supplied metadata fields that govern surface array dimensions and their relationship to available shader model capabilities. The core problem manifests when the vmw_surface_metadata structure receives an array_size parameter directly from userspace without adequate bounds checking or validation against hardware-specific constraints.
The technical flaw involves a critical missing input validation step where the array_size field from userspace is not properly constrained according to the available Shader Model capabilities of the target graphics hardware. This represents a classic buffer overflow vulnerability pattern and falls under the CWE-129 weakness category, which specifically addresses insufficient input validation leading to potential memory corruption or arbitrary code execution. The vulnerability exploits the lack of proper bounds checking that should occur when processing surface metadata structures passed from userspace to kernel space, creating an attack surface where malicious actors could manipulate graphics operations through crafted array_size values.
The operational impact of this vulnerability extends beyond simple denial of service scenarios as it potentially enables privilege escalation and arbitrary code execution within the kernel context. When the graphics driver processes surfaces with malformed array_size parameters, it may traverse invalid memory locations or corrupt kernel data structures, leading to system instability or complete compromise. The exploitation becomes particularly dangerous because graphics drivers often run with elevated privileges and maintain direct hardware access capabilities, making this vulnerability a prime target for attackers seeking to gain root access or execute malicious code within the kernel space.
Mitigation strategies should implement comprehensive input validation at the kernel level where the vmw_surface_metadata array_size parameter is processed. The solution requires enforcing strict bounds checking that correlates the incoming array_size value against the maximum supported array size for the specific Shader Model version currently active on the hardware. This approach aligns with the ATT&CK technique T1068 which involves exploiting vulnerabilities in operating system or software components to gain elevated privileges. Additionally, implementing proper memory access controls and employing kernel address space layout randomization techniques can further reduce the exploitability of this class of vulnerability while maintaining system stability and performance.
The fix should incorporate runtime validation that dynamically determines available hardware capabilities and applies appropriate constraints to userspace inputs before any processing occurs. This validation must consider both the absolute maximum array sizes supported by the graphics hardware and the specific limitations imposed by the active shader model configuration. Regular security audits of kernel subsystems handling user-supplied data, particularly those involving graphics rendering pipelines, should be conducted to identify similar validation gaps that may exist in other components. The resolution of this vulnerability demonstrates the critical importance of maintaining robust input validation practices throughout kernel space operations where user-space applications interact with hardware abstraction layers and graphics processing units.