CVE-2026-23236 in Linux
Summary
by MITRE • 03/04/2026
In the Linux kernel, the following vulnerability has been resolved:
fbdev: smscufx: properly copy ioctl memory to kernelspace
The UFX_IOCTL_REPORT_DAMAGE ioctl does not properly copy data from userspace to kernelspace, and instead directly references the memory, which can cause problems if invalid data is passed from userspace. Fix this all up by correctly copying the memory before accessing it within the kernel.
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Analysis
by VulDB Data Team • 06/24/2026
The vulnerability identified as CVE-2026-23236 resides within the Linux kernel's framebuffer device driver, specifically in the smscufx subsystem that handles USB frame buffer devices. This issue manifests in the improper handling of memory operations during ioctl system calls, creating a critical security gap that could be exploited by malicious actors. The vulnerability affects the UFX_IOCTL_REPORT_DAMAGE ioctl command which is designed to report damage to framebuffer regions, but fails to properly validate and copy memory from userspace to kernelspace before processing.
The technical flaw stems from a direct memory reference pattern rather than proper memory copying mechanisms within the kernel's memory management subsystem. When userspace applications invoke the UFX_IOCTL_REPORT_DAMAGE ioctl command, the kernel fails to perform adequate memory validation and copying operations. Instead of using safe kernel memory copy functions such as copy_from_user or similar mechanisms, the code directly references userspace memory addresses, creating a potential attack surface where malformed data from untrusted sources can cause kernel memory corruption. This pattern violates fundamental kernel security principles and creates opportunities for privilege escalation or system compromise.
The operational impact of this vulnerability extends beyond simple memory corruption, as it represents a classic kernel memory safety issue that can lead to arbitrary code execution within kernel space. Attackers could potentially exploit this flaw by crafting malicious ioctl parameters that, when processed by the kernel, result in memory corruption, kernel panic, or more insidiously, allow for privilege escalation attacks. The vulnerability affects systems running Linux kernel versions that include the smscufx framebuffer driver, particularly those utilizing USB frame buffer devices or embedded systems that rely on this specific hardware abstraction layer. The issue demonstrates a failure in input validation and memory management practices that aligns with CWE-121, which describes stack-based buffer overflow conditions, though the specific manifestation occurs in kernel memory management rather than traditional stack operations.
Mitigation strategies for this vulnerability must focus on proper kernel memory handling practices and input validation. The fix implemented in the kernel resolves the issue by ensuring that all data received from userspace is properly copied to kernel space before any processing occurs, using appropriate kernel memory management functions. System administrators should prioritize applying the relevant kernel updates that contain the patched smscufx driver implementation, as this vulnerability represents a high-severity risk that could be exploited by attackers with local access or potentially remote exploitation in specific configurations. The remediation approach follows established security best practices for kernel development and aligns with ATT&CK technique T1068, which covers local privilege escalation through kernel vulnerabilities, making proper kernel memory management essential for maintaining system integrity. Organizations should also consider implementing additional monitoring and access controls around framebuffer device interfaces to detect potential exploitation attempts and maintain defense-in-depth strategies against similar memory safety issues.