Medium · published March 25, 2026
In the Linux kernel, the following vulnerability has been resolved:
net: vxlan: fix nd_tbl NULL dereference when IPv6 is disabled
When booting with the 'ipv6.disable=1' parameter, the nd_tbl is never
initialized because inet6_init() exits before ndisc_init() is called
which initializes it. If an IPv6 packet is injected into the interface,
route_shortcircuit() is called and a NULL pointer dereference happens on
neigh_lookup().
BUG: kernel NULL pointer dereference, address: 0000000000000380
Oops: Oops: 0000 [#1] SMP NOPTI
[...]
RIP: 0010:neigh_lookup+0x20/0x270
[...]
Call Trace:
<TASK>
vxlan_xmit+0x638/0x1ef0 [vxlan]
dev_hard_start_xmit+0x9e/0x2e0
__dev_queue_xmit+0xbee/0x14e0
packet_sendmsg+0x116f/0x1930
__sys_sendto+0x1f5/0x200
__x64_sys_sendto+0x24/0x30
do_syscall_64+0x12f/0x1590
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Fix this by adding an early check on route_shortcircuit() when protocol
is ETH_P_IPV6. Note that ipv6_mod_enabled() cannot be used here because
VXLAN can be built-in even when IPv6 is built as a module.
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | ≥ 3.12, < 5.10.253 | 5.10.253 |
| linux/linux_kernel | ≥ 5.11, < 5.15.203 | 5.15.203 |
| linux/linux_kernel | ≥ 5.16, < 6.1.167 | 6.1.167 |
| linux/linux_kernel | ≥ 6.2, < 6.6.130 | 6.6.130 |
| linux/linux_kernel | ≥ 6.7, < 6.12.77 | 6.12.77 |
| linux/linux_kernel | ≥ 6.13, < 6.18.17 | 6.18.17 |
| linux/linux_kernel | ≥ 6.19, < 6.19.7 | 6.19.7 |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |