CVE-2026-23293

Summary

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.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/649e2bb74da54c96cf20729001e283626a2fefa0
• https://git.kernel.org/stable/c/dc3e62cf3bbf66280a907ec379f373d0c3b8b2bc
• https://git.kernel.org/stable/c/b5190fcd75a1f1785c766a8d1e44d3938e168f45
• https://git.kernel.org/stable/c/5f93e6b4d12bd3a4517a6d447ea675f448f21434
• https://git.kernel.org/stable/c/f0373e9317bc904e7bdb123d3106fe4f3cea2fb7
• https://git.kernel.org/stable/c/fbbd2118982c55fb9b0a753ae0cf7194e77149fb
• https://git.kernel.org/stable/c/abcd48ecdeb2e12eccb8339a35534c757782afcd
• https://git.kernel.org/stable/c/168ff39e4758897d2eee4756977d036d52884c7e

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