CVE-2026-23396

In the Linux kernel, the following vulnerability has been resolved:

wifi: mac80211: fix NULL deref in mesh_matches_local()

mesh_matches_local() unconditionally dereferences ie->mesh_config to compare mesh configuration parameters. When called from mesh_rx_csa_frame(), the parsed action-frame elements may not contain a Mesh Configuration IE, leaving ie->mesh_config NULL and triggering a kernel NULL pointer dereference.

The other two callers are already safe:

• ieee80211_mesh_rx_bcn_presp() checks !elems->mesh_config before calling mesh_matches_local()
• mesh_plink_get_event() is only reached through mesh_process_plink_frame(), which checks !elems->mesh_config, too

mesh_rx_csa_frame() is the only caller that passes raw parsed elements to mesh_matches_local() without guarding mesh_config. An adjacent attacker can exploit this by sending a crafted CSA action frame that includes a valid Mesh ID IE but omits the Mesh Configuration IE, crashing the kernel.

The captured crash log:

Oops: general protection fault, probably for non-canonical address … KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] Workqueue: events_unbound cfg80211_wiphy_work […] Call Trace: ? __pfx_mesh_matches_local (net/mac80211/mesh.c:65) ieee80211_mesh_rx_queued_mgmt (net/mac80211/mesh.c:1686) […] ieee80211_iface_work (net/mac80211/iface.c:1754 net/mac80211/iface.c:1802) […] cfg80211_wiphy_work (net/wireless/core.c:426) process_one_work (net/kernel/workqueue.c:3280) ? assign_work (net/kernel/workqueue.c:1219) worker_thread (net/kernel/workqueue.c:3352) ? __pfx_worker_thread (net/kernel/workqueue.c:3385) kthread (net/kernel/kthread.c:436) […] ret_from_fork_asm (net/arch/x86/entry/entry_64.S:255)

This patch adds a NULL check for ie->mesh_config at the top of mesh_matches_local() to return false early when the Mesh Configuration IE is absent.

Weakness

The product dereferences a pointer that it expects to be valid but is NULL.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/0a4da176ae4b4e075a19c00d3e269cfd5e05a813
• https://git.kernel.org/stable/c/14a4fd13657a3f2489db6566f081adfb27a49c64
• https://git.kernel.org/stable/c/44699c6cdfce80a0f296b54ae9314461e3e41b3d
• https://git.kernel.org/stable/c/74de6fa472b03bc8cde0a081484e9960bcbda568
• https://git.kernel.org/stable/c/7c55a3deaf7eaaafa2546f8de7fed19382a0a116
• https://git.kernel.org/stable/c/a90279e7f7ea0b7e923a1c5ebee9a6b78b6d1004
• https://git.kernel.org/stable/c/c1e3f2416fb27c816ce96d747d3e784e31f4d95c
• https://git.kernel.org/stable/c/c73bb9a2d33bf81f6eecaa0f474b6c6dbe9855bd