The Linux kernel’s VXLAN implementation contains a data‑race flaw where the neighbor hardware address field can be updated asynchronously and is protected by a seqlock. When the route_shortcircuit() function reads this field without holding the lock, torn or partially updated MAC addresses can be observed. This corrupts the MAC address used for VXLAN packet forwarding, potentially leading to mis‑routing, packet loss, or denial of service for applications relying on VXLAN tunnels. The weakness arises from improper synchronization in concurrent code, identified as CWE-367.

All Linux kernel releases older than the commit that introduces neigh_ha_snapshot() into route_shortcircuit() are affected. This includes the default kernel builds provided by most major Linux distributions that have not yet applied the patch. Because the information does not specify affected versions, users should verify whether their installed kernel contains the fixed code, which can be done by checking the presence of the specific commit in the kernel source.

The vulnerability receives a CVSS score of 10, indicating critical severity. The EPSS score is less than 1%, and it is not listed in CISA’s KEV catalog, suggesting that exploitation is unlikely at present. Based on the description, it is inferred that an attacker would likely need local or elevated privileges to manipulate neighbor entries and trigger the race, making remote exploitation more difficult. Nevertheless, if successfully triggered, the impact remains high, and the potential for disruptive network traffic exists.