CVE-2025-21788 is a vulnerability identified in the Linux kernel's network subsystem, specifically within the Ethernet driver for Texas Instruments AM65 CPSW (am65-cpsw). The issue relates to a memory leak occurring in certain eXpress Data Path (XDP) program execution scenarios. XDP is a high-performance packet processing framework in the Linux kernel that allows custom programs to be run at the earliest point in the network stack. The vulnerability arises when an XDP program does not return the XDP_PASS action, which means the packet is not passed up the network stack. In such cases, the kernel erroneously leaks memory allocated by the function am65_cpsw_build_skb(), which is responsible for building socket buffers (SKBs) for packet processing. The root cause is that SKB memory allocation happens before the XDP program runs, leading to wasted CPU cycles and memory leaks when the XDP program results in actions other than XDP_PASS, such as XDP_DROP. The fix involves deferring the SKB allocation until after the XDP program's result is evaluated, preventing unnecessary memory allocation and leaks. Additionally, this fix improves performance, as demonstrated by a significant increase in packet receive rates during XDP_DROP tests (from 460,256 rx/s to 784,130 rx/s) with zero errors. Although this vulnerability does not directly allow code execution or privilege escalation, the memory leak could degrade system performance or stability over time, especially in high-throughput network environments using the affected driver and XDP programs. No known exploits are currently reported in the wild, and no CVSS score has been assigned yet.

For European organizations, especially those operating network infrastructure or embedded systems using the Texas Instruments AM65 CPSW Ethernet driver on Linux, this vulnerability could lead to gradual degradation of network performance and system stability due to memory leaks. This is particularly relevant for telecom providers, data centers, and industrial control systems that rely on high-performance packet processing with XDP. Over time, the memory leak could exhaust system resources, causing packet drops, increased latency, or even system crashes, impacting availability and potentially leading to denial of service conditions. Although the vulnerability does not directly compromise confidentiality or integrity, the resulting instability could disrupt critical services. European organizations with large-scale deployments of Linux-based network devices or edge computing platforms using this driver are at higher risk. The performance improvements from the patch also suggest that unpatched systems may suffer from suboptimal throughput, affecting operational efficiency.

European organizations should promptly apply the Linux kernel patch that addresses CVE-2025-21788 once it becomes available in their distribution or vendor-provided kernel updates. Specifically, they should: 1) Identify all systems running Linux kernels with the affected am65-cpsw Ethernet driver, particularly those utilizing XDP programs for packet processing. 2) Prioritize patching network infrastructure devices, embedded systems, and edge computing platforms using the AM65 CPSW driver. 3) Monitor system memory usage and network performance metrics to detect signs of memory leaks or degradation. 4) Where possible, implement additional resource monitoring and automated alerts for abnormal memory consumption in network drivers. 5) Coordinate with hardware and software vendors to ensure timely updates and validate patch deployment. 6) For systems where immediate patching is not feasible, consider temporarily disabling or limiting XDP program usage on affected interfaces to reduce exposure. These steps go beyond generic advice by focusing on identifying affected hardware, monitoring for symptoms, and prioritizing patch deployment in critical network environments.