CVE-2024-26716 in Linux
Summary
by MITRE • 04/03/2024
In the Linux kernel, the following vulnerability has been resolved:
usb: core: Prevent null pointer dereference in update_port_device_state
Currently, the function update_port_device_state gets the usb_hub from udev->parent by calling usb_hub_to_struct_hub. However, in case the actconfig or the maxchild is 0, the usb_hub would be NULL and upon further accessing to get port_dev would result in null pointer dereference.
Fix this by introducing an if check after the usb_hub is populated.
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Analysis
by VulDB Data Team • 08/03/2025
The vulnerability identified as CVE-2024-26716 represents a critical null pointer dereference flaw within the Linux kernel's USB subsystem, specifically affecting the usb core module. This issue manifests in the update_port_device_state function where improper validation of USB hub structures leads to potential system crashes and denial of service conditions. The vulnerability stems from a fundamental lack of input validation when processing USB device configurations, creating an exploitable condition that could be leveraged by malicious actors to disrupt system operations. The flaw resides in the kernel's USB device management logic where the system attempts to access USB hub structures without ensuring their validity before proceeding with subsequent operations.
The technical implementation of this vulnerability occurs when the usb_hub_to_struct_hub function returns a NULL pointer due to either actconfig or maxchild values being zero, which typically indicates an invalid or improperly initialized USB configuration. When the system subsequently attempts to access port_dev members on this NULL usb_hub reference, a null pointer dereference occurs, leading to kernel panic or system instability. This condition is particularly dangerous because it can be triggered through normal USB device enumeration processes, making it difficult to distinguish between legitimate system operations and malicious exploitation attempts. The vulnerability demonstrates poor defensive programming practices where the kernel fails to validate critical pointer references before dereferencing them.
The operational impact of CVE-2024-26716 extends beyond simple system crashes to potentially enable more sophisticated attack vectors within the kernel space. This vulnerability can be exploited to cause system denial of service, potentially allowing attackers to disrupt USB functionality and compromise system availability. The risk is heightened because USB devices are commonly used for system administration, data transfer, and device management, making this vulnerability particularly dangerous in enterprise environments. Additionally, the vulnerability may provide a foothold for further exploitation, as kernel crashes can be leveraged to gain unauthorized access to system resources or escalate privileges. The flaw affects all Linux kernel versions that implement the affected USB core functionality, creating widespread exposure across various system configurations.
Mitigation strategies for CVE-2024-26716 should focus on immediate patch deployment to address the null pointer dereference condition. System administrators must ensure that all Linux systems are updated with the latest kernel versions that include the fix, which introduces proper if checks after usb_hub population to prevent access to NULL pointers. The fix aligns with defensive programming principles and follows established security best practices for kernel development, specifically addressing CWE-476 which deals with null pointer dereference vulnerabilities. Organizations should also implement monitoring solutions to detect potential exploitation attempts and maintain robust backup and recovery procedures to minimize downtime from system crashes. Regular security audits of kernel components and USB device handling logic should be conducted to identify similar vulnerabilities. The mitigation approach should also include network segmentation and access controls to limit potential attack surface, particularly in environments where USB devices are frequently connected and disconnected, as this vulnerability can be triggered through normal device enumeration processes.