CVE-2023-52445 is a use-after-free vulnerability found in the Linux kernel's media subsystem, specifically affecting the pvrusb2 driver. The pvrusb2 driver handles certain USB-based TV tuner devices. The vulnerability arises during the lifecycle management of the driver's context object. When the driver module is loaded, a kernel thread (kthread) is created to run the function pvr2_context_thread_func. This thread may invoke pvr2_context_destroy, which frees the context object using kfree(). However, this destruction can occur before the USB hub_event handler notifies the driver of disconnection events. This timing discrepancy leads to a use-after-free condition, where the driver may attempt to access memory that has already been freed, causing invalid reads or potential kernel memory corruption. The patch introduced adds a sanity check to prevent the invalid read detected by syzbot, a kernel fuzzing tool, by ensuring the context is valid before accessing it during disconnection handling. Although no known exploits are reported in the wild, the vulnerability could be triggered by manipulating USB device connection and disconnection events, potentially leading to kernel crashes or privilege escalation if exploited. The affected versions are specific Linux kernel commits identified by the hash e5be15c63804e05b5a94197524023702a259e308, indicating a narrow range of affected kernel builds. The vulnerability was publicly disclosed on February 22, 2024, and is confirmed by the Linux project and CISA enrichment, but no CVSS score has been assigned yet.

For European organizations, this vulnerability poses a risk primarily to systems running Linux kernels with the affected pvrusb2 driver enabled and in use, such as media servers, embedded devices, or workstations utilizing USB TV tuner hardware. Exploitation could lead to denial of service via kernel crashes or potentially privilege escalation, undermining system integrity and availability. This is particularly critical for organizations relying on Linux-based infrastructure for media processing, broadcasting, or specialized USB hardware integration. The vulnerability could be leveraged by attackers with local access or via malicious USB devices, which may be introduced intentionally or accidentally. Given the widespread use of Linux in European enterprises, including government, telecommunications, and media sectors, the impact could be significant if exploited. However, the absence of known exploits and the specific hardware dependency somewhat limit the immediate risk. Nonetheless, the potential for kernel-level compromise necessitates prompt attention to prevent escalation and maintain operational continuity.

European organizations should prioritize updating their Linux kernels to versions that include the patch for CVE-2023-52445. Since the vulnerability is tied to the pvrusb2 driver, organizations should audit their systems to identify any usage of USB TV tuner devices or related hardware that relies on this driver. If such hardware is not in use, disabling or blacklisting the pvrusb2 module can reduce the attack surface. For systems requiring the driver, ensure kernel updates are applied promptly. Additionally, implement strict USB device control policies, including device whitelisting and monitoring of USB device connections, to prevent unauthorized or malicious USB devices from being connected. Employ kernel hardening techniques such as Kernel Address Space Layout Randomization (KASLR) and Kernel Page Table Isolation (KPTI) to mitigate exploitation impact. Regularly monitor system logs for unusual kernel errors or crashes that might indicate exploitation attempts. Finally, incorporate this vulnerability into vulnerability management and patching workflows to ensure timely remediation across all Linux systems.