Enabling the RX Buffer Unavailable (RBUE) interrupt in the XGMAC2 driver causes a runaway loop of interrupts whenever the DMA runs out of receive descriptors. This leads to billions of interrupts for only a few million processed packets, exhausting CPU cycles and preventing normal packet reception. The weakness is a classic case of uncontrolled resource consumption. The RBUE handler merely sets a flag that the normal RX completion interrupt already performs, so the additional interrupt offers no benefit and instead triggers a sustained interrupt storm that can effectively freeze the system under heavy inbound traffic. Because the RBUE handler alone cannot recover from a low‑memory situation, the storm persists even when the page pool is exhausted, resulting in a full denial of service for network traffic.

The issue impacts Linux kernel builds that support XGMAC2 devices, specifically noted on the Agilex5 platform. Any kernel using the stmmac driver with the default RBUE interrupt enabled will experience the interrupt storm under heavy RX pressure. The patch removes RBUE from the default interrupt masks across XGMAC2 variants, but the affected devices and kernel versions are not explicitly enumerated in the advisory. Users running kernel versions that include the unmodified XGMAC2 driver should be aware that their NIC may be susceptible to this resource exhaustion behavior during heavy inbound traffic.

The CVSS score is 7.5, indicating high severity; the EPSS score of 0.00426 (less than 1%) reflects a very low likelihood of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog, indicating no known public exploits currently. Based on the description, an attacker with control over the NIC traffic load, either locally or remotely, can exploit the kernel’s driver to trigger a sustained interrupt storm, leading to a denial‑of‑service of network traffic. No special privileges beyond the ability to generate heavy inbound traffic are required, making this a practical high‑impact vector for systems exposed to uncontrolled network input.