CVE-2024-26611 is a vulnerability identified in the Linux kernel related to the handling of zero-copy (ZC) XDP (eXpress Data Path) sockets, specifically involving the use of multi-buffer BPF (Berkeley Packet Filter) helpers. The issue arises when a packet is shrunk using the bpf_xdp_adjust_tail() helper function while the memory type is set to MEM_TYPE_XSK_BUFF_POOL. Under these conditions, a NULL pointer dereference occurs, leading to a kernel crash (NULL pointer dereference at address 0x34). This is triggered because the __xdp_return() function receives a NULL xdp_buff argument, which is expected to be consumed by the xsk_buff_free() call. The root cause is that in the zero-copy case, the node representing the fragment being removed is not properly pulled out of the xskb_list, causing the NULL pointer dereference. The fix involves introducing appropriate xsk helpers to manage the node operations correctly within bpf_xdp_adjust_tail(). This vulnerability can cause a denial of service (DoS) by crashing the kernel, impacting system stability and availability. The vulnerability affects Linux kernel versions identified by the commit hash 24ea50127ecf0efe819c1f6230add27abc6ca9d9 and is present in kernel 6.6.0+ as per the crash logs. There are no known exploits in the wild at this time, and no CVSS score has been assigned yet. The vulnerability requires the use of XDP sockets with zero-copy buffers and BPF programs, which are typically used in high-performance networking environments.

For European organizations, the impact of CVE-2024-26611 primarily concerns systems running Linux kernels with zero-copy XDP socket configurations, which are common in data centers, telecom infrastructure, and cloud providers that rely on high-performance packet processing. The vulnerability can lead to kernel crashes and system downtime, resulting in denial of service. This can disrupt critical network functions, degrade service availability, and potentially impact business operations relying on real-time data processing or network throughput. Organizations using Linux-based network appliances, edge computing devices, or servers with XDP-enabled applications are at risk. The vulnerability does not directly lead to privilege escalation or data leakage but can be exploited to cause service interruptions. Given the increasing adoption of Linux in telecom and cloud infrastructure across Europe, especially in sectors like finance, healthcare, and government, the operational impact could be significant if exploited or triggered unintentionally. The lack of known exploits reduces immediate risk, but the presence of this bug in kernel-level networking code means that accidental triggers or targeted attacks could cause outages.

European organizations should prioritize updating their Linux kernels to versions that include the fix for CVE-2024-26611 as soon as patches become available from their Linux distribution vendors. Until patches are applied, organizations should audit their use of XDP zero-copy sockets and BPF programs, especially those that use bpf_xdp_adjust_tail() with MEM_TYPE_XSK_BUFF_POOL buffers. Disabling or limiting the use of zero-copy XDP socket features in non-critical environments can reduce exposure. Network administrators should monitor kernel logs for signs of NULL pointer dereference crashes related to XDP and investigate any unexpected kernel oops events. Implementing robust kernel crash recovery and failover mechanisms will help mitigate service disruption risks. Additionally, organizations should engage with their Linux distribution security advisories and apply vendor-specific patches promptly. For environments where kernel upgrades are delayed, consider isolating affected systems or restricting access to reduce the risk of exploitation or accidental triggering.