Linux Kernel VXLAN Component Null Pointer Dereference Vulnerability

A null pointer dereference vulnerability has been identified in the Linux kernel's VXLAN implementation, specifically in versions prior to 6.17.0. This issue arises when an incoming packet attempts to refresh a Forwarding Database (FDB) entry that is linked to an FDB nexthop group, rather than a remote destination. This scenario typically occurs in EVPN deployments with learning enabled. The vulnerability can be exploited by sending a crafted packet that triggers the FDB entry refresh, leading to a kernel crash.

Impact

Exploitation of this vulnerability causes a kernel NULL pointer dereference, which can lead to a system crash.

Reproduction

The vulnerability can be reproduced by creating a VXLAN interface with learning enabled and adding a static FDB entry that points to an FDB nexthop group. Then, send a packet that refreshes the FDB entry, causing the null pointer dereference.

Remediation

Users can upgrade to Linux kernel version 6.17.0 or later, where this vulnerability has been fixed.