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CVE-2026-23381

net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.77, and 2 more
None on Exploit-DB, Metasploit or GitHub

Summary

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.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From ed842faeb2bd49256f00485402f3113205f91d30 · fixed in a9d712ccfeef737c0e700a4b5b98f310e07b6b60; From ed842faeb2bd49256f00485402f3113205f91d30 · fixed in a5c56e65b685360dd3f2278aeff8c21061feb665; From ed842faeb2bd49256f00485402f3113205f91d30 · fixed in 7a894eb5de246d79f13105c55a67381039a24d44; From ed842faeb2bd49256f00485402f3113205f91d30 · fixed in a12cdaa3375f0bd3c8f4e564be7c143529abfe5b; From ed842faeb2bd49256f00485402f3113205f91d30 · fixed in aa73deb3b6b730ec280d45b3f423bfa9e17bc122; From ed842faeb2bd49256f00485402f3113205f91d30 · fixed in 33dec6f10777d5a8f71c0a200f690da5ae3c2e55; From ed842faeb2bd49256f00485402f3113205f91d30 · fixed in 20ef5c25422f97dd09d751e5ae6c18406cdc78e6; From ed842faeb2bd49256f00485402f3113205f91d30 · fixed in e5e890630533bdc15b26a34bb8e7ef539bdf1322

  • Linux Linux

    4.15

  • KernelLinux

    From 4.15.0 · fixed in 5.10.253; From 5.11.0 · fixed in 5.15.203; From 5.16.0 · fixed in 6.1.167; From 6.2.0 · fixed in 6.6.130; From 6.7.0 · fixed in 6.12.77; From 6.13.0 · fixed in 6.18.17; From 6.19.0 · fixed in 6.19.7

References 8

git.kernel.org