CVE-2025-22101 is a vulnerability identified in the Linux kernel's networking stack, specifically within the net subsystem's libwx module responsible for handling transmit (Tx) Layer 4 (L4) checksum offloading. The issue arises because the hardware supports L4 checksum offload only for TCP, UDP, and SCTP protocols. However, due to a bug, the kernel erroneously sets the Tx checksum offload flag for other protocols as well. This incorrect flag setting causes the transmit ring buffer to hang, effectively stalling packet transmission for affected protocols. The root cause is that the kernel attempts to offload checksum calculation to hardware for unsupported protocols, leading to a deadlock in the Tx ring. The fix involves computing the checksum in software for these unsupported protocols instead of relying on hardware offload. This vulnerability affects Linux kernel versions identified by the given commit hash (3403960cdf86c967442dccc2bec981e0093f716e), and the issue was publicly disclosed on April 16, 2025. There are no known exploits in the wild at the time of publication, and no CVSS score has been assigned yet. The vulnerability impacts the availability of network communications by causing transmit ring hangs, which can lead to denial of service conditions on affected systems.

For European organizations, this vulnerability poses a risk primarily to the availability of network services running on Linux systems using affected kernel versions. Since Linux is widely deployed across servers, cloud infrastructure, and embedded devices in Europe, any system handling network traffic with protocols other than TCP, UDP, or SCTP could experience network transmission stalls. This could disrupt critical services, especially in sectors relying on real-time or high-throughput networking such as telecommunications, finance, healthcare, and public administration. The impact is particularly significant for infrastructure providers and data centers that use Linux-based routers, firewalls, or network appliances. Although no known exploits exist yet, the potential for denial of service through transmit ring hangs could be leveraged by attackers to degrade service availability or cause operational disruptions. The confidentiality and integrity of data are not directly impacted by this vulnerability, but the availability degradation could indirectly affect business continuity and service reliability.

European organizations should prioritize patching affected Linux kernel versions as soon as updates become available from trusted sources or Linux distributions. Since the vulnerability involves incorrect hardware offload flag settings, organizations should audit their network configurations and monitor for unusual network interface behavior or transmit ring stalls. Network administrators can temporarily mitigate risk by disabling L4 checksum offloading for unsupported protocols if feasible, though this may impact performance. Implementing robust network monitoring and alerting to detect transmit ring hangs or packet transmission failures will help identify exploitation attempts or operational issues early. Additionally, organizations should maintain strict control over kernel updates and validate kernel versions in use across their infrastructure to ensure no vulnerable versions remain in production. For embedded or specialized Linux devices, coordination with vendors for timely firmware/kernel updates is critical. Finally, incorporating this vulnerability into incident response and risk management frameworks will prepare teams to respond effectively if exploitation attempts arise.