Linux Kernel VXLAN Devices Vulnerable to Improper Proxy Handling by Vendor Linux

CVE-2025-39850

What is CVE-2025-39850?

A vulnerability exists in Linux Kernel's VXLAN devices where the proxy option, when enabled, can lead to improper handling of ARP requests and IPv6 Neighbor Solicitation messages. If a valid neighbor entry is configured but associated with an incorrect FDB nexthop group, the kernel may erroneously assume the MAC address points to a valid remote destination. This misjudgment can result in a Null Pointer Dereference (NPD) when the system tries to dereference a non-existent remote destination. To mitigate this risk, the code should implement checks to confirm the existence of the remote destination before proceeding.

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