CVE-2024-26675 is a vulnerability identified in the Linux kernel, specifically related to the Point-to-Point Protocol (PPP) asynchronous driver component (ppp_async). The issue revolves around the Maximum Receive Unit (MRU) size parameter, which was not properly limited, potentially allowing an attacker to specify an excessively large MRU value. This improper limitation could lead to a warning or error in the kernel memory allocation function __alloc_pages(), as indicated by the WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp) warning triggered by syzbot, a kernel fuzzing tool. The root cause is that the MRU value was not capped at 64K, which is the maximum safe size for this parameter. The vulnerability was addressed by applying a sanity check in the ppp_async_ioctl function, specifically for the PPPIOCSMRU ioctl command, to limit the MRU to 64K, consistent with a prior fix in the ppp driver. The technical details show that the flaw could cause abnormal behavior in kernel memory allocation routines, potentially leading to kernel warnings or faults during packet buffer allocation (skbuff). The vulnerability affects Linux kernel versions around 6.8.0-rc2 and likely other versions using the affected ppp_async driver code. There is no evidence of known exploits in the wild at this time, and no CVSS score has been assigned yet. The vulnerability is primarily a denial-of-service or stability issue caused by improper input validation in kernel space, which could be triggered by a local or remote attacker capable of sending crafted PPP packets or ioctl commands to the ppp_async driver interface.

For European organizations, the impact of CVE-2024-26675 depends on the deployment of Linux systems using PPP asynchronous drivers, which are typically found in embedded devices, legacy network equipment, or specialized communication systems that rely on PPP links. If exploited, this vulnerability could cause kernel warnings or crashes, leading to denial of service (DoS) conditions on affected systems. This could disrupt network connectivity or critical services relying on PPP links, impacting operational continuity. While the vulnerability does not appear to allow privilege escalation or remote code execution, the resulting instability could be leveraged in targeted attacks against network infrastructure or embedded devices in sectors such as telecommunications, industrial control systems, or IoT deployments common in European industries. The lack of known exploits reduces immediate risk, but the potential for DoS and system instability means organizations should prioritize patching, especially those with legacy or specialized Linux-based network equipment. Additionally, the vulnerability could complicate incident response and system reliability in critical environments.

European organizations should implement the following specific mitigation measures: 1) Identify and inventory all Linux systems running kernel versions affected by this vulnerability, focusing on those utilizing PPP asynchronous drivers. 2) Apply the official Linux kernel patches that introduce the MRU size limitation to 64K in the ppp_async_ioctl handler as soon as they become available, or upgrade to a kernel version that includes this fix. 3) For embedded or legacy devices where kernel upgrades are not feasible, consider disabling PPP asynchronous support if not required, or restrict access to the PPP interfaces to trusted users and systems only. 4) Monitor kernel logs and system alerts for WARN_ON_ONCE_GFP or related memory allocation warnings that could indicate attempted exploitation or instability. 5) Implement network-level controls to limit or filter PPP traffic from untrusted sources to reduce exposure. 6) Engage with device vendors and maintainers to ensure timely updates and support for affected hardware running Linux kernels with this vulnerability. 7) Incorporate this vulnerability into vulnerability management and patching cycles, prioritizing systems critical to network operations and industrial processes.