CVE-2026-23381
MediumCVSS 5.5Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
A NULL pointer dereference vulnerability was found in the Linux kernel's bridge br_do_suppress_nd() function. It occurs when IPv6 is disabled via ipv6.disable=1 and an ICMPv6 Neighbor Discovery packet reaches the bridge, causing a kernel crash.
Risk Assessment
An attacker can trigger a kernel panic by sending a crafted ICMPv6 packet to a network bridge when IPv6 is disabled. This can lead to network service disruption and availability loss.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit replacing IS_ENABLED(IPV6) with ipv6_mod_enabled()). If patching is not possible, temporarily disable the neigh_suppress feature on the bridge.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: net: bridge: 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. Then, if neigh_suppress is enabled and an ICMPv6 Neighbor Discovery packet reaches the bridge, br_do_suppress_nd() will dereference ipv6_stub->nd_tbl which is NULL, passing it to neigh_lookup(). This causes a kernel NULL pointer dereference. BUG: kernel NULL pointer dereference, address: 0000000000000268 Oops: 0000 [#1] PREEMPT SMP NOPTI [...] RIP: 0010:neigh_lookup+0x16/0xe0 [...] Call Trace: <IRQ> ? neigh_lookup+0x16/0xe0 br_do_suppress_nd+0x160/0x290 [bridge] br_handle_frame_finish+0x500/0x620 [bridge] br_handle_frame+0x353/0x440 [bridge] __netif_receive_skb_core.constprop.0+0x298/0x1110 __netif_receive_skb_one_core+0x3d/0xa0 process_backlog+0xa0/0x140 __napi_poll+0x2c/0x170 net_rx_action+0x2c4/0x3a0 handle_softirqs+0xd0/0x270 do_softirq+0x3f/0x60 Fix this by replacing IS_ENABLED(IPV6) call with ipv6_mod_enabled() in the callers. This is in essence disabling NS/NA suppression when IPv6 is disabled.