A flaw in the Cortina Ethernet driver for Linux kernels causes the driver to acknowledge RX overrun interrupts incorrectly. The driver reads the overrun flag from interrupt status register 4 but clears it with a bit from status register 0. For GMAC0 this clears the overrun flag of GMAC1, and for GMAC1 the shift leaves no bit set, so the flag remains asserted on the wrong port or never clears. The result is that the interrupt continues to fire, buffers are drained, and packets are dropped, potentially rendering the affected interface unusable. The bug does not provide any remote code execution or privilege escalation capability.

The issue affects Linux kernel builds that include the Cortina Ethernet driver for the GMAC0 and GMAC1 ports. Any distribution or custom kernel that has not incorporated the upstream patch is potentially vulnerable. Versions are not listed in the advisory, so all builds containing the vulnerable driver code should be considered at risk until updated.

EPSS indicates a probability of exploitation below 1 %, and the flaw is not listed in CISA KEV, so widespread exploitation is unlikely. The vulnerability requires local or privileged kernel access to trigger the incorrect interrupt handling; there is no documented remote attack vector. The impact is limited to packet loss or local denial of service on an affected network interface. Based on the effect on availability, the CVSS would be in the moderate to high range, but lacking a published score we note the severity is significant for network‑critical systems.