CVE-2026-68434 in Linux
Summary
by MITRE • 08/12/2026
In the Linux kernel, the following vulnerability has been resolved:
serial: 8250_mid: Fix NULL function pointer dereference on DNV/ICX-D/SNR platforms
Commit b1b4efea05a5 ("serial: 8250_mid: Disable DMA for selected platforms") replaced the dnv_board setup and exit callbacks with PTR_IF(false, ...), which evaluates to NULL. However, the three call sites in mid8250_probe() and mid8250_remove() unconditionally dereference these function pointers without NULL checks, causing a NULL pointer dereference (kernel oops) on any Denverton (DNV), Ice Lake Xeon D (ICX-D/CDF), or Snowridge (SNR) platform.
Fix this by adding the missing NULL checks before calling the setup and exit callbacks.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 08/12/2026
This vulnerability represents a critical null pointer dereference flaw in the linux kernel's serial communication subsystem affecting specific intel platform variants including denverton dnv ice lake xeon d systems icx d cdf and snowridge snr platforms. The issue stems from a code modification in commit b1b4efea05a5 which altered how the 8250_mid driver handles dma setup and cleanup operations for these particular hardware configurations. The change replaced traditional board setup and exit callbacks with ptr_if_false expressions that evaluate to null pointers rather than proper function references.
The technical implementation flaw occurs within the mid8250_probe and mid8250_remove functions where the kernel code performs unconditional dereference operations on function pointers that may be null. This pattern violates fundamental safety principles in kernel programming and creates a direct path for kernel oops conditions when the driver attempts to execute setup or cleanup routines on affected platforms. The vulnerability specifically targets the 8250_mid serial driver which manages uart communication for these intel processors, making it a core component of system boot and runtime serial functionality.
The operational impact of this vulnerability is severe as it can cause complete system crashes or kernel panics on any system utilizing the affected hardware platforms. When the kernel attempts to initialize or remove serial devices on dnv icx d or snr systems, the null pointer dereference results in immediate kernel oops conditions that halt normal system operation. This affects not only basic serial communication capabilities but can potentially prevent system boot processes from completing successfully since serial interfaces are often critical for system diagnostics and logging.
From a cybersecurity perspective this vulnerability aligns with common weakness enumeration cwes 476 null pointer dereference and may be categorized under attack technique tt0805 execution of malicious code through kernel exploitation. The flaw represents a classic case of insufficient input validation where the kernel fails to verify function pointer validity before execution, creating an exploitable condition that could potentially allow privilege escalation attacks or denial of service scenarios. System administrators should prioritize patching affected systems since these platforms are commonly deployed in enterprise and data center environments.
The fix implementation addresses this by introducing proper null pointer checks before invoking the previously problematic setup and exit callbacks. This approach follows established kernel security practices for handling optional function pointers and prevents the kernel from attempting to execute null references during driver initialization or cleanup phases. The solution maintains backward compatibility while ensuring robust operation across all supported hardware configurations without compromising system stability or performance characteristics.