CVE-2023-52567 is a vulnerability identified in the Linux kernel's serial driver, specifically within the 8250_port driver responsible for handling serial port communications. The flaw arises when the driver attempts to use IRQ polling mode (where irq = 0) and the Interrupt Identification Register (IIR) indicates an interrupt has occurred in the 8250 hardware. Under these conditions, the IRQ data pointer can be NULL. The vulnerable code does not check for this NULL pointer before dereferencing it, leading to a kernel NULL pointer dereference and a consequent kernel Oops (crash). This occurs because the driver mistakenly attempts to wake the system based on an IRQ event that originated from a timer interrupt path, where the system is likely already awake. The issue manifests as a kernel panic or crash, disrupting normal system operation. The vulnerability affects multiple versions of the Linux kernel as indicated by the commit hashes listed, and has been publicly disclosed without a CVSS score or known exploits in the wild at this time. The fix involves adding a check to verify the IRQ data is not NULL before use, preventing the kernel crash.

For European organizations, this vulnerability poses a risk primarily to systems running affected Linux kernel versions with serial port hardware using the 8250 driver in IRQ polling mode. The impact is a denial of service through kernel crashes, which can disrupt critical services, especially in industrial, embedded, or server environments relying on serial communications. Systems such as network infrastructure devices, industrial control systems, or legacy hardware interfaces that use serial ports could be affected. While this vulnerability does not appear to allow privilege escalation or remote code execution, the resulting system instability could lead to downtime, data loss, or interruption of business-critical operations. Organizations in sectors like manufacturing, telecommunications, and critical infrastructure in Europe that deploy Linux-based systems with serial port dependencies should be particularly vigilant.

European organizations should promptly apply the official Linux kernel patches that address this vulnerability by adding the necessary NULL pointer checks in the serial8250 driver. For systems where immediate patching is not feasible, administrators should audit the use of serial ports configured with IRQ polling (irq=0) and consider disabling IRQ polling mode if possible. Monitoring kernel logs for serial8250 related Oops or crashes can help detect attempted exploitation or manifestation of this bug. Additionally, organizations should ensure robust backup and recovery procedures are in place to mitigate the impact of unexpected kernel crashes. For embedded or specialized devices, coordinate with vendors to obtain updated firmware or kernel versions that include the fix. Finally, maintain an inventory of Linux systems and their kernel versions to prioritize patching efforts effectively.